Revert "Use browsers JSON.parse for parsing JSON (#3)"

tests/corelib/json_leading_zeros_test.dart

-// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-// This is a trimmed-down version of json_test to isolate a difference between
-// IE and other runtimes.
-
-library json_test;
-
-import "dart:json";
-
-bool badFormat(e) => e is FormatException;
-
-void testThrows(json) {
-  Expect.throws(() => parse(json), badFormat);
-}
-
-testNumbers() {
-  // Positive tests for number formats.
-  var integerList = ["0","9","9999"];
-  var signList = ["", "-"];
-  var fractionList = ["", ".0", ".1", ".99999"];
-  var exponentList = [""];
-  for (var exphead in ["e", "E", "e-", "E-", "e+", "E+"]) {
-    for (var expval in ["0", "1", "200"]) {
-      exponentList.add("$exphead$expval");
-    }
-  }
-
-  // Negative tests (syntax error).
-  // testError thoroughly tests the given parts with a lot of valid
-  // values for the other parts.
-  testError({signs, integers, fractions, exponents}) {
-    def(value, defaultValue) {
-      if (value == null) return defaultValue;
-      if (value is List) return value;
-      return [value];
-    }
-    signs = def(signs, signList);
-    integers = def(integers, integerList);
-    fractions = def(fractions, fractionList);
-    exponents = def(exponents, exponentList);
-    for (var integer in integers) {
-      for (var sign in signs) {
-        for (var fraction in fractions) {
-          for (var exponent in exponents) {
-            var literal = "$sign$integer$fraction$exponent";
-            testThrows(literal);
-          }
-        }
-      }
-    }
-  }
-  // Initial zero only allowed for zero integer part.
-  testError(integers: ["00", "01"]);
-}
-
-main() {
-  testNumbers();
-}