Reland [swarming] Isolate v8 testing.

test/unittests/unittests.gyp

 # Copyright 2014 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.
 
 {
   'variables': {
     'v8_code': 1,
   },
   'includes': ['../../build/toolchain.gypi', '../../build/features.gypi'],
   'targets': [
@@ skipping 160 matching lines @@
           },
         }],
         ['v8_wasm!=0', {
           'dependencies': [
             '../../third_party/wasm/test/unittests/wasm/wasm.gyp:wasm_unittests',
           ],
         }],
       ],
     },
   ],
+  'conditions': [
+    ['test_isolation_mode != "noop"', {
+      'targets': [
+        {
+          'target_name': 'unittests_run',
+          'type': 'none',
+          'dependencies': [
+            'unittests',
+          ],
+          'includes': [
+            '../../build/isolate.gypi',
+          ],
+          'sources': [
+            'unittests.isolate',
+          ],
+        },
+      ],
+    }],
+  ],
 }