[swarming] Isolate webkit and optimize_for_size.

test/optimize_for_size.isolate

Index: test/optimize_for_size.isolate
diff --git a/test/default.isolate b/test/optimize_for_size.isolate
similarity index 73%
copy from test/default.isolate
copy to test/optimize_for_size.isolate
index 68044cf15b76cd7735c4b1b48eb1c5069e3be396..aa7f57036efe9b8f293939b535972d762ecbd6aa 100644
--- a/test/default.isolate
+++ b/test/optimize_for_size.isolate
@@ -5,9 +5,7 @@
   'includes': [
     'cctest/cctest.isolate',
     'intl/intl.isolate',
-    'message/message.isolate',
     'mjsunit/mjsunit.isolate',
-    'preparser/preparser.isolate',
-    'unittests/unittests.isolate',
+    'webkit/webkit.isolate',
   ],
 }