Declare more functions returing a MaybeObject* with MUST_USE_RESULT.

src/objects.h

 // Copyright 2012 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 6121 matching lines @@
   DECL_ACCESSORS(sec, Object)
   // [cache stamp]: sample of the date cache stamp at the
   // moment when local fields were cached.
   DECL_ACCESSORS(cache_stamp, Object)
 
   // Casting.
   static inline JSDate* cast(Object* obj);
 
   // Returns the date field with the specified index.
   // See FieldIndex for the list of date fields.
-  static MaybeObject* GetField(Object* date, Smi* index);
+  static Object* GetField(Object* date, Smi* index);
 
   void SetValue(Object* value, bool is_value_nan);
 
 
   // Dispatched behavior.
 #ifdef OBJECT_PRINT
   inline void JSDatePrint() {
     JSDatePrint(stdout);
   }
   void JSDatePrint(FILE* out);
@@ skipping 2507 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_