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 b3704df698970eb140f939f5e2a759112ac26833..f49a10586d08ec14248a1c67d566bd694c7db30a 100644
--- a/src/handles.cc
+++ b/src/handles.cc
@@ -905,4 +905,18 @@ DeferredHandles* DeferredHandleScope::Detach() {
 }
 
 
+void AddWeakObjectToCodeDependency(Heap* heap,
+                                   Handle<Object> object,
+                                   Handle<Code> code) {
+  if (!heap->weak_object_to_code()->IsHashTable()) {
+    heap->set_weak_object_to_code(
+        *heap->isolate()->factory()->NewWeakHashTable(16));
+  }
+  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