Convert url_unittests to run exclusively on Swarming

url/url.gyp

 # Copyright 2013 The Chromium 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': {
     'chromium_code': 1,
   },
   'includes': [
     'url_srcs.gypi',
@@ skipping 105 matching lines @@
               '..',
             ],
           },
           'defines': [
             'URL_IMPLEMENTATION',
             'USE_ICU_ALTERNATIVES_ON_ANDROID=1',
           ],
         },
       ],
     }],
+    ['test_isolation_mode != "noop"', {
+      'targets': [
+        {
+          'target_name': 'url_unittests_run',
+          'type': 'none',
+          'dependencies': [
+            'url_unittests',
+          ],
+          'includes': [
+            '../build/isolate.gypi',
+          ],
+          'sources': [
+            'url_unittests.isolate',
+          ],
+        },
+      ],
+    }],
   ],
 }