Fixes #408

lib/runtime/dart/convert.js

 dart_library.library('dart/convert', null, /* Imports */[
   "dart/_runtime",
   'dart/core',
   'dart/async',
   'dart/typed_data',
   'dart/_internal',
   'dart/collection'
 ], /* Lazy imports */[
 ], function(exports, dart, core, async, typed_data, _internal, collection) {
   'use strict';
@@ skipping 1032 matching lines @@
     methods: () => ({
       convert: [dart.dynamic, [core.String]],
       startChunkedConversion: [StringConversionSink, [core.Sink$(core.Object)]],
       bind: [async.Stream$(core.Object), [async.Stream$(core.String)]]
     })
   });
   function _parseJson(source, reviver) {
     if (!(typeof source == 'string')) dart.throw(new core.ArgumentError(source));
     let parsed = null;
     try {
-      parsed = JSON.parse(source);
+      parsed = dart.global.JSON.parse(source);
     } catch (e) {
       dart.throw(new core.FormatException(String(e)));
     }
 
     if (reviver == null) {
       return _convertJsonToDartLazy(parsed);
     } else {
       return _convertJsonToDart(parsed, reviver);
     }
   }
@@ skipping 1740 matching lines @@
   exports.LineSplitter = LineSplitter;
   exports.StringConversionSink = StringConversionSink;
   exports.ClosableStringSink = ClosableStringSink;
   exports.UNICODE_REPLACEMENT_CHARACTER_RUNE = UNICODE_REPLACEMENT_CHARACTER_RUNE;
   exports.UNICODE_BOM_CHARACTER_RUNE = UNICODE_BOM_CHARACTER_RUNE;
   exports.Utf8Codec = Utf8Codec;
   exports.UTF8 = UTF8;
   exports.Utf8Encoder = Utf8Encoder;
   exports.Utf8Decoder = Utf8Decoder;
 });