ExtendStorageStub added, it is aimed for extending objects backing store when it runs out of space.

src/interface-descriptors.h

Index: src/interface-descriptors.h
diff --git a/src/interface-descriptors.h b/src/interface-descriptors.h
index b773c916ecbff19be72d97f42d792848d36bc653..66575b6892626fe427c982c9e8b98aa81700e92b 100644
--- a/src/interface-descriptors.h
+++ b/src/interface-descriptors.h
@@ -16,6 +16,7 @@ class PlatformInterfaceDescriptor;
 #define INTERFACE_DESCRIPTOR_LIST(V)          \
   V(Load)                                     \
   V(Store)                                    \
+  V(ExtendStorage)                            \
   V(ElementTransitionAndStore)                \
   V(Instanceof)                               \
   V(VectorLoadICTrampoline)                   \
@@ -213,6 +214,20 @@ class StoreDescriptor : public CallInterfaceDescriptor {
 };
 
 
+class ExtendStorageDescriptor : public StoreDescriptor {
+ public:
+  DECLARE_DESCRIPTOR(ExtendStorageDescriptor, StoreDescriptor)
+
+  enum ParameterIndices {
+    kReceiverIndex,
+    kMapIndex,
+    kValueIndex,
+    kParameterCount
+  };
+  static const Register MapRegister();
+};
+
+
 class ElementTransitionAndStoreDescriptor : public StoreDescriptor {
  public:
   DECLARE_DESCRIPTOR(ElementTransitionAndStoreDescriptor, StoreDescriptor)