Make objects embedded in optimized code weak.

src/handles.cc

Index: src/handles.cc
diff --git a/src/handles.cc b/src/handles.cc
index 054dde38eb6ca149cfe7cbbf01c8acde9313c6f2..20fe116dde996afe8fd1a8b8ff4ce89c82c9cd76 100644
--- a/src/handles.cc
+++ b/src/handles.cc
@@ -881,4 +881,15 @@ DeferredHandles* DeferredHandleScope::Detach() {
 }
 
 
+void AddWeakObjectToCodeDependency(Heap* heap,
+                                   Handle<Object> object,
+                                   Handle<Code> code) {
+  heap->EnsureWeakObjectToCodeTable();
+  Handle<DependentCode> dep(heap->LookupWeakObjectToCodeDependency(*object));
+  dep = DependentCode::Insert(dep, DependentCode::kWeaklyEmbeddedGroup, code);
+  CALL_HEAP_FUNCTION_VOID(heap->isolate(),
+                          heap->AddWeakObjectToCodeDependency(*object, *dep));
+}
+
+
 } }  // namespace v8::internal