AllocationSite objects weakly linked for traversal

src/x64/lithium-x64.h

Index: src/x64/lithium-x64.h
diff --git a/src/x64/lithium-x64.h b/src/x64/lithium-x64.h
index 62f65aef41262e08f134e1c3ddc8cef5ee008b7d..32ee0b9d31daf38d44bcd9683cfeb8d2b22297e8 100644
--- a/src/x64/lithium-x64.h
+++ b/src/x64/lithium-x64.h
@@ -121,6 +121,7 @@ class LCodeGen;
   V(IsUndetectableAndBranch)                    \
   V(Label)                                      \
   V(LazyBailout)                                \
+  V(LinkObjectInList)                           \
   V(LoadContextSlot)                            \
   V(LoadExternalArrayPointer)                   \
   V(LoadFunctionPrototype)                      \
@@ -1620,6 +1621,23 @@ class LStoreGlobalGeneric: public LTemplateInstruction<0, 2, 0> {
 };
 
 
+class LLinkObjectInList: public LTemplateInstruction<0, 1, 0> {
+ public:
+  explicit LLinkObjectInList(LOperand* object) {
+    inputs_[0] = object;
+  }
+
+  LOperand* object() { return inputs_[0]; }
+
+  ExternalReference GetReference(Isolate* isolate);
+
+  DECLARE_CONCRETE_INSTRUCTION(LinkObjectInList, "link-object-in-list")
+  DECLARE_HYDROGEN_ACCESSOR(LinkObjectInList)
+
+  virtual void PrintDataTo(StringStream* stream);
+};
+
+
 class LLoadContextSlot: public LTemplateInstruction<1, 1, 0> {
  public:
   explicit LLoadContextSlot(LOperand* context) {