1 files changed, 28 insertions, 21 deletions

diff --git a/deps/v8/src/runtime.cc b/deps/v8/src/runtime.cc
index 2f1f54c696..b8133ae15e 100644
--- a/deps/v8/src/runtime.cc
+++ b/deps/v8/src/runtime.cc
@@ -6944,15 +6944,9 @@ static MaybeObject* Runtime_CompileForOnStackReplacement(Arguments args) {
   Handle<Code> check_code = check_stub.GetCode();
   Handle<Code> replacement_code(
       Builtins::builtin(Builtins::OnStackReplacement));
-  // Iterate the unoptimized code and revert all the patched stack checks.
-  for (RelocIterator it(*unoptimized, RelocInfo::kCodeTargetMask);
-       !it.done();
-       it.next()) {
-    RelocInfo* rinfo = it.rinfo();
-    if (rinfo->target_address() == replacement_code->entry()) {
-      Deoptimizer::RevertStackCheckCode(rinfo, *check_code);
-    }
-  }
+  Deoptimizer::RevertStackCheckCode(*unoptimized,
+                                    *check_code,
+                                    *replacement_code);
 
   // Allow OSR only at nesting level zero again.
   unoptimized->set_allow_osr_at_loop_nesting_level(0);
@@ -7049,7 +7043,7 @@ static MaybeObject* Runtime_PushCatchContext(Arguments args) {
 }
 
 
-static MaybeObject* Runtime_LookupContext(Arguments args) {
+static MaybeObject* Runtime_DeleteContextSlot(Arguments args) {
   HandleScope scope;
   ASSERT(args.length() == 2);
 
@@ -7059,16 +7053,31 @@ static MaybeObject* Runtime_LookupContext(Arguments args) {
   int index;
   PropertyAttributes attributes;
   ContextLookupFlags flags = FOLLOW_CHAINS;
-  Handle<Object> holder =
-      context->Lookup(name, flags, &index, &attributes);
+  Handle<Object> holder = context->Lookup(name, flags, &index, &attributes);
 
-  if (index < 0 && !holder.is_null()) {
-    ASSERT(holder->IsJSObject());
-    return *holder;
+  // If the slot was not found the result is true.
+  if (holder.is_null()) {
+    return Heap::true_value();
   }
 
-  // No intermediate context found. Use global object by default.
-  return Top::context()->global();
+  // If the slot was found in a context, it should be DONT_DELETE.
+  if (holder->IsContext()) {
+    return Heap::false_value();
+  }
+
+  // The slot was found in a JSObject, either a context extension object,
+  // the global object, or an arguments object.  Try to delete it
+  // (respecting DONT_DELETE).  For consistency with V8's usual behavior,
+  // which allows deleting all parameters in functions that mention
+  // 'arguments', we do this even for the case of slots found on an
+  // arguments object.  The slot was found on an arguments object if the
+  // index is non-negative.
+  Handle<JSObject> object = Handle<JSObject>::cast(holder);
+  if (index >= 0) {
+    return object->DeleteElement(index, JSObject::NORMAL_DELETION);
+  } else {
+    return object->DeleteProperty(*name, JSObject::NORMAL_DELETION);
+  }
 }
 
 
@@ -7141,8 +7150,7 @@ static ObjectPair LoadContextSlotHelper(Arguments args, bool throw_error) {
   int index;
   PropertyAttributes attributes;
   ContextLookupFlags flags = FOLLOW_CHAINS;
-  Handle<Object> holder =
-      context->Lookup(name, flags, &index, &attributes);
+  Handle<Object> holder = context->Lookup(name, flags, &index, &attributes);
 
   // If the index is non-negative, the slot has been found in a local
   // variable or a parameter. Read it from the context object or the
@@ -7209,8 +7217,7 @@ static MaybeObject* Runtime_StoreContextSlot(Arguments args) {
   int index;
   PropertyAttributes attributes;
   ContextLookupFlags flags = FOLLOW_CHAINS;
-  Handle<Object> holder =
-      context->Lookup(name, flags, &index, &attributes);
+  Handle<Object> holder = context->Lookup(name, flags, &index, &attributes);
 
   if (index >= 0) {
     if (holder->IsContext()) {