Remove usage of dart:json.

samples/third_party/dromaeo/tests/dom-modify-html.dart

 library dromaeo;
 import 'dart:async';
 import 'dart:html';
-import 'dart:json' as json;
+import "dart:convert";
 import 'dart:math' as Math;
 part 'Common.dart';
 part 'RunnerSuite.dart';
 
 void main() {
   final int num = 400;
   var random = new Math.Random();
 
   String str = 'null';
-  // Very ugly way to build up the string, but let's mimic JS version as much as possible.
+  // Very ugly way to build up the string, but let's mimic JS version as much as
+  // possible.
   for (int i = 0; i < 1024; i++) {
-    str = "$str${new String.fromCharCodes([((25 * random.nextDouble()) + 97).toInt()])}";
+    str += new String.fromCharCode(((25 * random.nextDouble()) + 97).toInt());

[Emily Fortuna, 2013/08/28 21:09:54]

Are these two forms identical, perf-wise? I'm not certain what's going on "under
the hood"

[floitsch, 2013/08/28 21:12:15]

The new one could be faster (although I'm not sure we already implemented it).
If speed is an issue it shouldn't use string-concatenation, but a string-buffer.

[Emily Fortuna, 2013/08/28 21:19:01]

Agreed StringBuffer is the fastest way for sure-- I think they were trying to
keep this test similar to the original JS version so that they could compare
apples-to...almost apples. :-)

   }
 
   List<Node> elems = <Node>[];
 
   // Try to force real results.
   var ret;
 
   final htmlstr = document.body.innerHtml;
 
   new Suite(window, 'dom-modify')
@@ skipping 35 matching lines @@
     .test('appendChild', () {
       for (int i = 0; i < elems.length; i++)
         document.body.append(elems[i]);
     })
     .test('insertBefore', () {
       for (int i = 0; i < elems.length; i++)
         document.body.insertBefore(elems[i], document.body.firstChild);
     })
     .end();
 }