[json] replace remaining json.js code with C++ builtins.

test/mjsunit/debug-script.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 66 matching lines @@
 assertTrue(extension_count == 2 || extension_count == 3);
 // This script and mjsunit.js has been loaded.  If using d8, d8 loads
 // a normal script during startup too.
 assertTrue(normal_count == 2 || normal_count == 3);
 
 // Test a builtins script.
 var math_script = Debug.findScript('native math.js');
 assertEquals('native math.js', math_script.name);
 assertEquals(Debug.ScriptType.Native, math_script.type);
 
-// Test a builtins delay loaded script.
-var date_delay_script = Debug.findScript('native json.js');
-assertEquals('native json.js', date_delay_script.name);
-assertEquals(Debug.ScriptType.Native, date_delay_script.type);
-
 // Test a debugger script.
 var debug_delay_script = Debug.findScript('native debug.js');
 assertEquals('native debug.js', debug_delay_script.name);
 assertEquals(Debug.ScriptType.Native, debug_delay_script.type);
 
 // Test an extension script.
 var extension_gc_script = Debug.findScript('v8/gc');
 if (extension_gc_script) {
   assertEquals('v8/gc', extension_gc_script.name);
   assertEquals(Debug.ScriptType.Extension, extension_gc_script.type);
 }
 
 // Test a normal script.
 var debug_script = Debug.findScript(/debug-script.js/);
 assertTrue(/debug-script.js/.test(debug_script.name));
 assertEquals(Debug.ScriptType.Normal, debug_script.type);
 
 // Check a nonexistent script.
 var dummy_script = Debug.findScript('dummy.js');
 assertTrue(typeof dummy_script == 'undefined');
 
 Debug.setListener(null);