Use JSON.stringify to serialize debugger messages

test/mjsunit/mirror-unresolved-function.js

 // Copyright 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 24 matching lines @@
     this.refs_[tmp[i].handle] = tmp[i];
   }
 }
 
 MirrorRefCache.prototype.lookup = function(handle) {
   return this.refs_[handle];
 }
 
 var mirror = new debug.UnresolvedFunctionMirror("f");
 var serializer = debug.MakeMirrorSerializer();
-var json = serializer.serializeValue(mirror);
-var refs = new MirrorRefCache(serializer.serializeReferencedObjects());
+var json = JSON.stringify(serializer.serializeValue(mirror));
+var refs = new MirrorRefCache(
+    JSON.stringify(serializer.serializeReferencedObjects()));
 
 // Check the mirror hierachy for unresolved functions.
 assertTrue(mirror instanceof debug.Mirror);
 assertTrue(mirror instanceof debug.ValueMirror);
 assertTrue(mirror instanceof debug.ObjectMirror);
 assertTrue(mirror instanceof debug.FunctionMirror);
 
 // Check the mirror properties for unresolved functions.
 assertTrue(mirror.isUnresolvedFunction());
 assertEquals('function', mirror.type());
@@ skipping 14 matching lines @@
 assertEquals(mirror.constructorFunction().handle(), fromJSON.constructorFunction.ref, 'Unexpected constructor function handle in JSON');
 assertEquals('undefined', refs.lookup(fromJSON.constructorFunction.ref).type, 'Unexpected constructor function type in JSON');
 assertEquals(mirror.protoObject().handle(), fromJSON.protoObject.ref, 'Unexpected proto object handle in JSON');
 assertEquals('undefined', refs.lookup(fromJSON.protoObject.ref).type, 'Unexpected proto object type in JSON');
 assertEquals(mirror.prototypeObject().handle(), fromJSON.prototypeObject.ref, 'Unexpected prototype object handle in JSON');
 assertEquals('undefined', refs.lookup(fromJSON.prototypeObject.ref).type, 'Unexpected prototype object type in JSON');
 assertFalse(fromJSON.resolved);
 assertEquals("f", fromJSON.name);
 assertFalse('inferredName' in fromJSON);
 assertEquals(void 0, fromJSON.source);