Add a weak property type to the virtual machine.

runtime/vm/object.cc

Index: runtime/vm/object.cc
diff --git a/runtime/vm/object.cc b/runtime/vm/object.cc
index e1f31d992e78312ec6788f01b486427afeaefd1e..a7fd6762491cf054aa3fb5476f5d1a1a02fd4743 100644
--- a/runtime/vm/object.cc
+++ b/runtime/vm/object.cc
@@ -598,6 +598,11 @@ RawError* Object::Init(Isolate* isolate) {
   RegisterClass(cls, "JSSyntaxRegExp", impl_script, core_impl_lib);
   pending_classes.Add(cls, Heap::kOld);
 
+  cls = Class::New<WeakProperty>();
+  object_store->set_weak_property_class(cls);
+  RegisterClass(cls, "WeakProperty", impl_script, core_impl_lib);
+  pending_classes.Add(cls, Heap::kOld);
+
   // Initialize the base interfaces used by the core VM classes.
   const Script& script = Script::Handle(Bootstrap::LoadScript());
 
@@ -938,6 +943,9 @@ void Object::InitFromSnapshot(Isolate* isolate) {
   cls = Class::New<JSRegExp>();
   object_store->set_jsregexp_class(cls);
 
+  cls = Class::New<WeakProperty>();
+  object_store->set_weak_property_class(cls);
+
   // Allocate pre-initialized values.
   Bool& bool_value = Bool::Handle();
   bool_value = Bool::New(true);
@@ -1587,7 +1595,7 @@ RawClass* Class::NewSignatureClass(const String& name,
 
 
 RawClass* Class::GetClass(intptr_t class_id, bool is_signature_class) {
-  if (class_id >= kIntegerCid && class_id <= kJSRegExpCid) {
+  if (class_id >= kIntegerCid && class_id <= kWeakPropertyCid) {
     return Isolate::Current()->class_table()->At(class_id);
   }
   if (class_id >= kNumPredefinedCids) {
@@ -11034,4 +11042,24 @@ const char* JSRegExp::ToCString() const {
   return chars;
 }
 
+
+RawWeakProperty* WeakProperty::New(Heap::Space space) {
+  ASSERT(Isolate::Current()->object_store()->weak_property_class()
+         != Class::null());
+  WeakProperty& result = WeakProperty::Handle();
+  {
+    RawObject* raw = Object::Allocate(WeakProperty::kClassId,
+                                      WeakProperty::InstanceSize(),
+                                      space);
+    NoGCScope no_gc;
+    result ^= raw;
+  }
+  return result.raw();
+}
+
+
+const char* WeakProperty::ToCString() const {
+  return "WeakProperty";
+}
+
 }  // namespace dart