Only extend storage if FIELD

src/arm/stub-cache-arm.cc

Index: src/arm/stub-cache-arm.cc
diff --git a/src/arm/stub-cache-arm.cc b/src/arm/stub-cache-arm.cc
index 07bf4bb140a68be486c34926162f5639ea50765b..aebec2aeea3b34cf777c03dc6d92531454cbf4ea 100644
--- a/src/arm/stub-cache-arm.cc
+++ b/src/arm/stub-cache-arm.cc
@@ -547,7 +547,8 @@ void StubCompiler::GenerateStoreTransition(MacroAssembler* masm,
   ASSERT(object->IsJSGlobalProxy() || !object->IsAccessCheckNeeded());
 
   // Perform map transition for the receiver if necessary.
-  if (object->map()->unused_property_fields() == 0) {
+  if (details.type() == FIELD &&
+      object->map()->unused_property_fields() == 0) {
     // The properties must be extended before we can store the value.
     // We jump to a runtime call that extends the properties array.
     __ push(receiver_reg);