Make Failure inherit from MaybeObject instead of Object.

src/code-stubs.h

 // 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 88 matching lines @@
     NoCache,  // marker for stubs that do custom caching
     NUMBER_OF_IDS
   };
 
   // Retrieve the code for the stub. Generate the code if needed.
   Handle<Code> GetCode();
 
   // Retrieve the code for the stub if already generated.  Do not
   // generate the code if not already generated and instead return a
   // retry after GC Failure object.
-  Object* TryGetCode();
+  MUST_USE_RESULT MaybeObject* TryGetCode();
 
   static Major MajorKeyFromKey(uint32_t key) {
     return static_cast<Major>(MajorKeyBits::decode(key));
   }
   static int MinorKeyFromKey(uint32_t key) {
     return MinorKeyBits::decode(key);
   }
 
   // Gets the major key from a code object that is a code stub or binary op IC.
   static Major GetMajorKey(Code* code_stub) {
@@ skipping 707 matching lines @@
  private:
   StringCharCodeAtGenerator char_code_at_generator_;
   StringCharFromCodeGenerator char_from_code_generator_;
 
   DISALLOW_COPY_AND_ASSIGN(StringCharAtGenerator);
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_CODE_STUBS_H_