Update JSON.stringify to floor the space parameter (fixes issue 753)

src/json.js

 // Copyright 2009 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 223 matching lines @@
   if (IS_OBJECT(space)) {
     // Unwrap 'space' if it is wrapped
     if (IS_NUMBER_WRAPPER(space)) {
       space = $Number(space);
     } else if (IS_STRING_WRAPPER(space)) {
       space = $String(space);
     }
   }
   var gap;
   if (IS_NUMBER(space)) {
-    space = $Math.min(space, 10);
+    space = $Math.min(ToInteger(space), 10);
     gap = "";
     for (var i = 0; i < space; i++) {
       gap += " ";
     }
   } else if (IS_STRING(space)) {
     if (space.length > 10) {
       gap = space.substring(0, 10);
     } else {
       gap = space;
     }
   } else {
     gap = "";
   }
   return JSONSerialize('', {'': value}, replacer, stack, indent, gap);
 }
 
 function SetupJSON() {
   InstallFunctions($JSON, DONT_ENUM, $Array(
     "parse", JSONParse,
     "stringify", JSONStringify
   ));
 }
 
 SetupJSON();