Reland [swarming] Isolate v8 testing.

test/default.gyp

+# Copyright 2015 the V8 project authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+{
+  'conditions': [
+    ['test_isolation_mode != "noop"', {
+      'targets': [
+        {
+          'target_name': 'default_run',
+          'type': 'none',
+          'dependencies': [
+            'cctest/cctest.gyp:cctest_run',
+            'intl/intl.gyp:intl_run',
+            'message/message.gyp:message_run',
+            'mjsunit/mjsunit.gyp:mjsunit_run',
+            'preparser/preparser.gyp:preparser_run',
+          ],
+          'includes': [
+            '../build/features.gypi',
+            '../build/isolate.gypi',
+          ],
+          'sources': [
+            'default.isolate',
+          ],
+        },
+      ],
+    }],
+  ],
+}