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();
+}