Fix GC issue in instanceof stub...

src/code-stubs.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 31 matching lines @@
     *code_out = Code::cast(Heap::code_stubs()->ValueAt(index));
     return true;
   }
   return false;
 }
 
 
 void CodeStub::GenerateCode(MacroAssembler* masm) {
   // Update the static counter each time a new code stub is generated.
   Counters::code_stubs.Increment();
+
   // Nested stubs are not allowed for leafs.
-  masm->set_allow_stub_calls(AllowsStubCalls());
+  AllowStubCallsScope allow_scope(masm, AllowsStubCalls());
+
   // Generate the code for the stub.
   masm->set_generating_stub(true);
   Generate(masm);
 }
 
 
 void CodeStub::RecordCodeGeneration(Code* code, MacroAssembler* masm) {
   code->set_major_key(MajorKey());
 
   OPROFILE(CreateNativeCodeRegion(GetName(),
@@ skipping 157 matching lines @@
   OS::SNPrintF(Vector<char>(name_, kMaxNameLength),
                "InstanceofStub%s%s%s",
                args,
                inline_check,
                return_true_false_object);
   return name_;
 }
 
 
 } }  // namespace v8::internal