Adds Simulator Longjmp and enables many tests for arm64.

runtime/vm/json_test.cc

 // Copyright (c) 2012, 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.
 
-// TODO(zra): Remove when tests are ready to enable.
-#include "platform/globals.h"
-#if !defined(TARGET_ARCH_ARM64)
-
 #include "platform/assert.h"
 #include "platform/json.h"
 #include "vm/json_stream.h"
 #include "vm/unit_test.h"
 
 namespace dart {
 
 
 TEST_CASE(JSON_ScanJSON) {
   const char* msg = "{ \"id\": 5, \"command\" : \"Debugger.pause\" }";
@@ skipping 315 matching lines @@
   js.SetOptions(&option_keys[0], &option_values[0], 3);
   EXPECT(js.num_options() == 3);
   EXPECT(!js.HasOption("lizard"));
   EXPECT(js.HasOption("dog"));
   EXPECT(js.HasOption("cat"));
   EXPECT(js.OptionIs("cat", "banana"));
   EXPECT(!js.OptionIs("dog", "banana"));
 }
 
 }  // namespace dart
-
-#endif  // !defined(TARGET_ARCH_ARM64)