Imported WebKit commit 6a4a1d32e1d779548c726c4826cba9d69eb87601 (http://svn.webkit.org/repository/webkit/trunk@136242)

Final import for the Qt 5.x series that implements the QtWebKit / QtWebKitWidgets split

Extra fixes will be cherry-picked.

Change-Id: I844f1ebb99c6d6b75db31d6538c2acd628e79681
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>

18 files changed, 182 insertions, 44 deletions

diff --git a/Source/WebCore/inspector/Inspector.json b/Source/WebCore/inspector/Inspector.json
index 635fa9415..a2094cbb9 100644
--- a/Source/WebCore/inspector/Inspector.json
+++ b/Source/WebCore/inspector/Inspector.json
@@ -1858,10 +1858,11 @@
             {
                 "name": "highlightNode",
                 "parameters": [
-                    { "name": "nodeId", "$ref": "NodeId", "description": "Identifier of the node to highlight." },
+                    { "name": "nodeId", "$ref": "NodeId", "optional": true, "description": "Identifier of the node to highlight." },
+                    { "name": "objectId", "$ref": "Runtime.RemoteObjectId", "optional": true, "description": "JavaScript object id of the node to be highlighted." },
                     { "name": "highlightConfig", "$ref": "HighlightConfig", "description": "A descriptor for the highlight appearance." }
                 ],
-                "description": "Highlights DOM node with given id."
+                "description": "Highlights DOM node with given id or with the given JavaScript object wrapper. Either nodeId or objectId must be specified."
             },
             {
                 "name": "hideHighlight",
diff --git a/Source/WebCore/inspector/InspectorDOMAgent.cpp b/Source/WebCore/inspector/InspectorDOMAgent.cpp
index 1b0893472..9b8890ac6 100644
--- a/Source/WebCore/inspector/InspectorDOMAgent.cpp
+++ b/Source/WebCore/inspector/InspectorDOMAgent.cpp
@@ -1066,12 +1066,19 @@ void InspectorDOMAgent::highlightRect(ErrorString*, int x, int y, int width, int
     m_overlay->highlightRect(adoptPtr(new IntRect(x, y, width, height)), *highlightConfig);
 }
 
-void InspectorDOMAgent::highlightNode(
-    ErrorString* errorString,
-    int nodeId,
-    const RefPtr<InspectorObject>& highlightInspectorObject)
-{
-    Node* node = nodeForId(nodeId);
+void InspectorDOMAgent::highlightNode(ErrorString* errorString, const int* nodeId, const String* objectId, const RefPtr<InspectorObject>& highlightInspectorObject)
+{
+    Node* node = 0;
+    if (nodeId) {
+        node = assertNode(errorString, *nodeId);
+    } else if (objectId) {
+        InjectedScript injectedScript = m_injectedScriptManager->injectedScriptForObjectId(*objectId);
+        node = injectedScript.nodeForObjectId(*objectId);
+        if (!node)
+            *errorString = "Node for given objectId not found";
+    } else
+        *errorString = "Either nodeId or objectId must be specified";
+
     if (!node)
         return;
 
diff --git a/Source/WebCore/inspector/InspectorDOMAgent.h b/Source/WebCore/inspector/InspectorDOMAgent.h
index 3b7265283..f7cc5fb18 100644
--- a/Source/WebCore/inspector/InspectorDOMAgent.h
+++ b/Source/WebCore/inspector/InspectorDOMAgent.h
@@ -141,7 +141,7 @@ public:
     virtual void pushNodeByPathToFrontend(ErrorString*, const String& path, int* nodeId);
     virtual void hideHighlight(ErrorString*);
     virtual void highlightRect(ErrorString*, int x, int y, int width, int height, const RefPtr<InspectorObject>* color, const RefPtr<InspectorObject>* outlineColor);
-    virtual void highlightNode(ErrorString*, int nodeId, const RefPtr<InspectorObject>& highlightConfig);
+    virtual void highlightNode(ErrorString*, const int* nodeId, const String* objectId, const RefPtr<InspectorObject>& highlightConfig);
     virtual void highlightFrame(ErrorString*, const String& frameId, const RefPtr<InspectorObject>* color, const RefPtr<InspectorObject>* outlineColor);
     virtual void moveTo(ErrorString*, int nodeId, int targetNodeId, const int* anchorNodeId, int* newNodeId);
     virtual void undo(ErrorString*);
diff --git a/Source/WebCore/inspector/front-end/ConsoleMessage.js b/Source/WebCore/inspector/front-end/ConsoleMessage.js
index 39e4f6b9c..64f1ca17b 100644
--- a/Source/WebCore/inspector/front-end/ConsoleMessage.js
+++ b/Source/WebCore/inspector/front-end/ConsoleMessage.js
@@ -351,12 +351,7 @@ WebInspector.ConsoleMessageImpl.prototype = {
 
         if (property.type === "object" && property.subtype === "node") {
             span.addStyleClass("console-formatted-preview-node");
-            var match = property.value.match(/([^#.]+)(#[^.]+)?(\..*)?/);
-            span.createChild("span", "webkit-html-tag-name").textContent = match[1];
-            if (match[2])
-                span.createChild("span", "webkit-html-attribute-value").textContent = match[2];
-            if (match[3])
-                span.createChild("span", "webkit-html-attribute-name").textContent = match[3];
+            WebInspector.DOMPresentationUtils.createSpansForNodeTitle(span, property.value);
             return;
         }
 
diff --git a/Source/WebCore/inspector/front-end/DOMAgent.js b/Source/WebCore/inspector/front-end/DOMAgent.js
index ef4869383..afbbd7655 100644
--- a/Source/WebCore/inspector/front-end/DOMAgent.js
+++ b/Source/WebCore/inspector/front-end/DOMAgent.js
@@ -1198,17 +1198,17 @@ WebInspector.DOMAgent.prototype = {
     /**
      * @param {?number} nodeId
      * @param {string=} mode
+     * @param {RuntimeAgent.RemoteObjectId=} objectId
      */
-    highlightDOMNode: function(nodeId, mode)
+    highlightDOMNode: function(nodeId, mode, objectId)
     {
         if (this._hideDOMNodeHighlightTimeout) {
             clearTimeout(this._hideDOMNodeHighlightTimeout);
             delete this._hideDOMNodeHighlightTimeout;
         }
 
-        this._highlightedDOMNodeId = nodeId;
-        if (nodeId)
-            DOMAgent.highlightNode(nodeId, this._buildHighlightConfig(mode));
+        if (objectId || nodeId)
+            DOMAgent.highlightNode(objectId ? undefined : nodeId, objectId, this._buildHighlightConfig(mode));
         else
             DOMAgent.hideHighlight();
     },
diff --git a/Source/WebCore/inspector/front-end/DOMExtension.js b/Source/WebCore/inspector/front-end/DOMExtension.js
index 162fa964d..5bfcd2233 100644
--- a/Source/WebCore/inspector/front-end/DOMExtension.js
+++ b/Source/WebCore/inspector/front-end/DOMExtension.js
@@ -195,6 +195,18 @@ Element.prototype.remove = function()
         this.parentElement.removeChild(this);
 }
 
+/**
+ * @param {Node} fromNode
+ * @param {Node} toNode
+ */
+function removeSubsequentNodes(fromNode, toNode)
+{
+    for (var node = fromNode; node && node !== toNode; ) {
+        var nodeToRemove = node;
+        node = node.nextSibling;
+        nodeToRemove.remove();
+    }
+}
 
 /**
  * @constructor
diff --git a/Source/WebCore/inspector/front-end/DOMPresentationUtils.js b/Source/WebCore/inspector/front-end/DOMPresentationUtils.js
index 905b78f9f..d70569dbe 100644
--- a/Source/WebCore/inspector/front-end/DOMPresentationUtils.js
+++ b/Source/WebCore/inspector/front-end/DOMPresentationUtils.js
@@ -76,6 +76,20 @@ WebInspector.DOMPresentationUtils.decorateNodeLabel = function(node, parentEleme
     parentElement.title = title;
 }
 
+/**
+ * @param {Element} container
+ * @param {string} nodeTitle
+ */
+WebInspector.DOMPresentationUtils.createSpansForNodeTitle = function(container, nodeTitle)
+{
+    var match = nodeTitle.match(/([^#.]+)(#[^.]+)?(\..*)?/);
+    container.createChild("span", "webkit-html-tag-name").textContent = match[1];
+    if (match[2])
+        container.createChild("span", "webkit-html-attribute-value").textContent = match[2];
+    if (match[3])
+        container.createChild("span", "webkit-html-attribute-name").textContent = match[3];
+}
+
 WebInspector.DOMPresentationUtils.linkifyNodeReference = function(node)
 {
     var link = document.createElement("span");
diff --git a/Source/WebCore/inspector/front-end/DefaultTextEditor.js b/Source/WebCore/inspector/front-end/DefaultTextEditor.js
index 08f48e08f..458e54552 100644
--- a/Source/WebCore/inspector/front-end/DefaultTextEditor.js
+++ b/Source/WebCore/inspector/front-end/DefaultTextEditor.js
@@ -2415,13 +2415,28 @@ WebInspector.TextEditorMainPanel.prototype = {
         // Remove damaged chunks from DOM and from textChunks model.
         var lastUndamagedChunk = firstDamagedChunkNumber > 0 ? this._textChunks[firstDamagedChunkNumber - 1] : null;
         var firstUndamagedChunk = lastDamagedChunkNumber + 1 < this._textChunks.length ? this._textChunks[lastDamagedChunkNumber + 1] : null;
+
         var removeDOMFromNode = lastUndamagedChunk ? lastUndamagedChunk.lastElement().nextSibling : this._container.firstChild;
         var removeDOMToNode = firstUndamagedChunk ? firstUndamagedChunk.firstElement() : null;
-        for (var node = removeDOMFromNode; node && node !== removeDOMToNode; ) {
-            var nodeToRemove = node;
-            node = node.nextSibling;
-            nodeToRemove.remove();
+
+        // Fast case - patch single expanded chunk that did not grow / shrink during edit.
+        if (!linesDiff && firstDamagedChunk === lastDamagedChunk && firstDamagedChunk._expandedLineRows) {
+            var lastUndamagedLineRow = lastDamagedChunk.expandedLineRow(oldRange.startLine - 1);
+            var firstUndamagedLineRow = firstDamagedChunk.expandedLineRow(oldRange.endLine + 1);
+            var localRemoveDOMFromNode = lastUndamagedLineRow ? lastUndamagedLineRow.nextSibling : removeDOMFromNode;
+            var localRemoveDOMToNode = firstUndamagedLineRow || removeDOMToNode;
+            removeSubsequentNodes(localRemoveDOMFromNode, localRemoveDOMToNode);
+            for (var i = newRange.startLine; i < newRange.endLine + 1; ++i) {
+                var row = firstDamagedChunk._createRow(i);
+                firstDamagedChunk._expandedLineRows[i - firstDamagedChunk.startLine] = row;
+                this._container.insertBefore(row, localRemoveDOMToNode);
+            }
+            firstDamagedChunk.updateCollapsedLineRow();
+            this._assertDOMMatchesTextModel();
+            return;
         }
+
+        removeSubsequentNodes(removeDOMFromNode, removeDOMToNode);
         this._textChunks.splice(firstDamagedChunkNumber, lastDamagedChunkNumber - firstDamagedChunkNumber + 1);
 
         // Compute damaged chunks span
diff --git a/Source/WebCore/inspector/front-end/MemoryStatistics.js b/Source/WebCore/inspector/front-end/MemoryStatistics.js
index d44cc65d0..aa83b1f01 100644
--- a/Source/WebCore/inspector/front-end/MemoryStatistics.js
+++ b/Source/WebCore/inspector/front-end/MemoryStatistics.js
@@ -314,10 +314,11 @@ WebInspector.MemoryStatistics.prototype = {
 
     _onClick: function(event)
     {
-        var x = event.x - event.target.offsetParent.offsetLeft
+        var x = event.x - event.target.offsetParent.offsetLeft;
         var i = this._recordIndexAt(x);
         var counter = this._counters[i];
-        this._timelinePanel.revealRecordAt(counter.time / 1000);
+        if (counter)
+            this._timelinePanel.revealRecordAt(counter.time / 1000);
     },
 
     _onMouseOut: function(event)
diff --git a/Source/WebCore/inspector/front-end/NativeMemorySnapshotView.js b/Source/WebCore/inspector/front-end/NativeMemorySnapshotView.js
index a9d046c3f..d43099c97 100644
--- a/Source/WebCore/inspector/front-end/NativeMemorySnapshotView.js
+++ b/Source/WebCore/inspector/front-end/NativeMemorySnapshotView.js
@@ -55,22 +55,49 @@ WebInspector.NativeMemorySnapshotView.prototype = {
 WebInspector.NativeSnapshotDataGrid = function(profile)
 {
     var columns = {
-        object: { title: WebInspector.UIString("Object"), width: "200px", disclosure: true, sortable: false },
-        size: { title: WebInspector.UIString("Size"), sortable: false },
+        name: { title: WebInspector.UIString("Object"), width: "200px", disclosure: true, sortable: true },
+        size: { title: WebInspector.UIString("Size"), sortable: true, sort: "descending" },
     };
     WebInspector.DataGrid.call(this, columns);
-    var totalNode = new WebInspector.NativeSnapshotNode(profile, profile);
+    this._totalNode = new WebInspector.NativeSnapshotNode(profile, profile);
     if (WebInspector.settings.showNativeSnapshotUninstrumentedSize.get()) {
         this.setRootNode(new WebInspector.DataGridNode(null, true));
-        this.rootNode().appendChild(totalNode)
-        totalNode.expand();
+        this.rootNode().appendChild(this._totalNode)
+        this._totalNode.expand();
     } else {
-        this.setRootNode(totalNode);
-        totalNode._populate();
+        this.setRootNode(this._totalNode);
+        this._totalNode._populate();
     }
+    this.addEventListener("sorting changed", this.sortingChanged.bind(this), this);
 }
 
 WebInspector.NativeSnapshotDataGrid.prototype = {
+    sortingChanged: function()
+    {
+        var expandedNodes = {};
+        this._totalNode._storeState(expandedNodes);
+        this._totalNode.removeChildren();
+        this._totalNode._populate();
+        this._totalNode._shouldRefreshChildren = true;
+        this._totalNode._restoreState(expandedNodes);
+    },
+
+    /**
+     * @param {MemoryAgent.MemoryBlock} nodeA
+     * @param {MemoryAgent.MemoryBlock} nodeB
+     */
+    _sortingFunction: function(nodeA, nodeB)
+    {
+        var sortColumnIdentifier = this.sortColumnIdentifier;
+        var sortAscending = this.sortOrder === "ascending";
+        var field1 = nodeA[sortColumnIdentifier];
+        var field2 = nodeB[sortColumnIdentifier];
+        var result = field1 < field2 ? -1 : (field1 > field2 ? 1 : 0);
+        if (!sortAscending)
+            result = -result;
+        return result;
+    },
+
     __proto__: WebInspector.DataGrid.prototype
 }
 
@@ -85,7 +112,7 @@ WebInspector.NativeSnapshotNode = function(nodeData, profile)
     this._nodeData = nodeData;
     this._profile = profile;
     var viewProperties = WebInspector.MemoryBlockViewProperties._forMemoryBlock(nodeData);
-    var data = { object: viewProperties._description, size: this._nodeData.size };
+    var data = { name: viewProperties._description, size: this._nodeData.size };
     var hasChildren = !!nodeData.children && nodeData.children.length !== 0;
     WebInspector.DataGridNode.call(this, data, hasChildren);
     this.addEventListener("populate", this._populate, this);
@@ -106,6 +133,40 @@ WebInspector.NativeSnapshotNode.prototype = {
     },
 
     /**
+     * @param {Object} expandedNodes
+     */
+    _storeState: function(expandedNodes)
+    {
+        if (!this.expanded)
+            return;
+        expandedNodes[this.uid()] = true;
+        for (var i in this.children)
+            this.children[i]._storeState(expandedNodes);
+    },
+
+    /**
+     * @param {Object} expandedNodes
+     */
+    _restoreState: function(expandedNodes)
+    {
+        if (!expandedNodes[this.uid()])
+            return;
+        this.expand();
+        for (var i in this.children)
+            this.children[i]._restoreState(expandedNodes);
+    },
+
+    /**
+     * @return {string}
+     */
+    uid: function()
+    {
+        if (!this._uid)
+            this._uid = (!this.parent || !this.parent.uid ? "" : this.parent.uid() || "") + "/" + this._nodeData.name;
+        return this._uid;
+    },
+
+    /**
      * @param {string} columnIdentifier
      * @return {Element}
      */
@@ -121,7 +182,7 @@ WebInspector.NativeSnapshotNode.prototype = {
             node = node.parent;
         }
 
-        var sizeKiB = this._nodeData.size / 1024;
+        var sizeKB = this._nodeData.size / 1024;
         var totalSize = this._profile.size;
         var percentage = this._nodeData.size / totalSize  * 100;
 
@@ -129,7 +190,7 @@ WebInspector.NativeSnapshotNode.prototype = {
         cell.className = columnIdentifier + "-column";
 
         var textDiv = document.createElement("div");
-        textDiv.textContent = Number.withThousandsSeparator(sizeKiB.toFixed(0)) + "\u2009" + WebInspector.UIString("KiB");
+        textDiv.textContent = Number.withThousandsSeparator(sizeKB.toFixed(0)) + "\u2009" + WebInspector.UIString("KB");
         textDiv.className = "size-text";
         cell.appendChild(textDiv);
 
@@ -157,11 +218,7 @@ WebInspector.NativeSnapshotNode.prototype = {
 
     _populate: function() {
         this.removeEventListener("populate", this._populate, this);
-        function comparator(a, b) {
-            return b.size - a.size;
-        }
-        if (this._nodeData !== this._profile)
-            this._nodeData.children.sort(comparator);
+        this._nodeData.children.sort(this.dataGrid._sortingFunction.bind(this.dataGrid));
         for (var node in this._nodeData.children) {
             var nodeData = this._nodeData.children[node];
             if (WebInspector.settings.showNativeSnapshotUninstrumentedSize.get() || nodeData.name !== "Other")
diff --git a/Source/WebCore/inspector/front-end/NavigatorView.js b/Source/WebCore/inspector/front-end/NavigatorView.js
index c9103bba2..b740bbf68 100644
--- a/Source/WebCore/inspector/front-end/NavigatorView.js
+++ b/Source/WebCore/inspector/front-end/NavigatorView.js
@@ -479,6 +479,8 @@ WebInspector.BaseNavigatorTreeElement.prototype = {
 
     set titleText(titleText)
     {
+        if (this._titleText === titleText)
+            return;
         this._titleText = titleText || "";
         if (this.titleElement)
             this.titleElement.textContent = this._titleText;
diff --git a/Source/WebCore/inspector/front-end/ObjectPropertiesSection.js b/Source/WebCore/inspector/front-end/ObjectPropertiesSection.js
index bcbf01386..e4be780f9 100644
--- a/Source/WebCore/inspector/front-end/ObjectPropertiesSection.js
+++ b/Source/WebCore/inspector/front-end/ObjectPropertiesSection.js
@@ -234,7 +234,7 @@ WebInspector.ObjectPropertyTreeElement.prototype = {
         } else if (this.property.value.type === "function" && typeof description === "string") {
             this.valueElement.textContent = /.*/.exec(description)[0].replace(/ +$/g, "");
             this.valueElement._originalTextContent = description;
-        } else
+        } else if (this.property.value.type !== "object" || this.property.value.subtype !== "node") 
             this.valueElement.textContent = description;
 
         if (this.property.wasThrown)
@@ -245,7 +245,12 @@ WebInspector.ObjectPropertyTreeElement.prototype = {
             this.valueElement.addStyleClass("console-formatted-" + this.property.value.type);
 
         this.valueElement.addEventListener("contextmenu", this._contextMenuFired.bind(this, this.property.value), false);
-        this.valueElement.title = description || "";
+        if (this.property.value.type === "object" && this.property.value.subtype === "node") {
+            WebInspector.DOMPresentationUtils.createSpansForNodeTitle(this.valueElement, this.property.value.description);
+            this.valueElement.addEventListener("mousemove", this._mouseMove.bind(this, this.property.value), false);
+            this.valueElement.addEventListener("mouseout", this._mouseOut.bind(this, this.property.value), false);
+        } else
+            this.valueElement.title = description || "";
 
         this.listItemElement.removeChildren();
 
@@ -270,6 +275,16 @@ WebInspector.ObjectPropertyTreeElement.prototype = {
     {
     },
 
+    _mouseMove: function(event)
+    {
+        this.property.value.highlightAsDOMNode();
+    },
+
+    _mouseOut: function(event)
+    {
+        this.property.value.hideDOMNodeHighlight();
+    },
+
     updateSiblings: function()
     {
         if (this.parent.root)
diff --git a/Source/WebCore/inspector/front-end/RemoteObject.js b/Source/WebCore/inspector/front-end/RemoteObject.js
index 3f080b352..35cbf1b6b 100644
--- a/Source/WebCore/inspector/front-end/RemoteObject.js
+++ b/Source/WebCore/inspector/front-end/RemoteObject.js
@@ -288,6 +288,16 @@ WebInspector.RemoteObject.prototype = {
             callback(0);
     },
 
+    highlightAsDOMNode: function()
+    {
+        WebInspector.domAgent.highlightDOMNode(undefined, undefined, this._objectId);
+    },
+
+    hideDOMNodeHighlight: function()
+    {
+        WebInspector.domAgent.hideDOMNodeHighlight();
+    },
+
     /**
      * @param {function(this:Object)} functionDeclaration
      * @param {Array.<RuntimeAgent.CallArgument>=} args
diff --git a/Source/WebCore/inspector/front-end/TabbedPane.js b/Source/WebCore/inspector/front-end/TabbedPane.js
index 18ba6186d..817b0539e 100644
--- a/Source/WebCore/inspector/front-end/TabbedPane.js
+++ b/Source/WebCore/inspector/front-end/TabbedPane.js
@@ -598,6 +598,8 @@ WebInspector.TabbedPaneTab.prototype = {
 
     set title(title)
     {
+        if (title === this._title)
+            return;
         this._title = title;
         if (this._titleElement)
             this._titleElement.textContent = title;
diff --git a/Source/WebCore/inspector/front-end/TestController.js b/Source/WebCore/inspector/front-end/TestController.js
index b46026199..bb400ed32 100644
--- a/Source/WebCore/inspector/front-end/TestController.js
+++ b/Source/WebCore/inspector/front-end/TestController.js
@@ -45,7 +45,7 @@ WebInspector.TestController.prototype = {
 
 WebInspector.evaluateForTestInFrontend = function(callId, script)
 {
-    WebInspector.isUnderTest = true;
+    window.isUnderTest = true;
     function invokeMethod()
     {
         try {
diff --git a/Source/WebCore/inspector/front-end/externs.js b/Source/WebCore/inspector/front-end/externs.js
index be792be6d..8c5a4ef8a 100644
--- a/Source/WebCore/inspector/front-end/externs.js
+++ b/Source/WebCore/inspector/front-end/externs.js
@@ -65,6 +65,8 @@ function postMessage(message) {}
 /** @type {*} */
 window.testRunner = null;
 
+window.isUnderTest = false;
+
 /**
  * @constructor
  */
diff --git a/Source/WebCore/inspector/front-end/inspector.css b/Source/WebCore/inspector/front-end/inspector.css
index 54bb4695b..d0fab33ba 100644
--- a/Source/WebCore/inspector/front-end/inspector.css
+++ b/Source/WebCore/inspector/front-end/inspector.css
@@ -1141,6 +1141,10 @@ ol.watch-expressions > li.hovered {
     color: black;
 }
 
+.console-formatted-node:hover {
+    background-color: rgba(56, 121, 217, 0.1);
+}
+
 .console-formatted-object .section, .console-formatted-node .section, .console-formatted-array .section {
     position: static;
 }
diff --git a/Source/WebCore/inspector/front-end/utilities.js b/Source/WebCore/inspector/front-end/utilities.js
index 043e886e9..b4bbec510 100644
--- a/Source/WebCore/inspector/front-end/utilities.js
+++ b/Source/WebCore/inspector/front-end/utilities.js
@@ -861,6 +861,7 @@ function importScript(scriptName)
     window.eval(xhr.responseText + "\n//@ sourceURL=" + scriptName);
 }
 
+window.isUnderTest = false;
 
 /**
  * Mutation observers leak memory. Keep track of them and disconnect
@@ -872,7 +873,7 @@ function NonLeakingMutationObserver(handler)
 {
     this._observer = new WebKitMutationObserver(handler);
     NonLeakingMutationObserver._instances.push(this);
-    if (!window.testRunner && !WebInspector.isUnderTest && !NonLeakingMutationObserver._unloadListener) {
+    if (!window.testRunner && !window.isUnderTest && !NonLeakingMutationObserver._unloadListener) {
         NonLeakingMutationObserver._unloadListener = function() {
             while (NonLeakingMutationObserver._instances.length)
                 NonLeakingMutationObserver._instances[NonLeakingMutationObserver._instances.length - 1].disconnect();