Support running http layout tests for workers in UI test framework.

BUG=none
TEST=This is a UI test.

Nicolas, could you please review DEPS? I added a couple of new lines to DEPS in order to fetch a copy the following directory into UI test data directory:
  LayoutTests/http/tests/resources
  LayoutTests/http/tests/workers
  LayoutTests/http/tests/xmlhttprequest


Review URL: http://codereview.chromium.org/147125

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@19502 0039d316-1c4b-4281-b951-d872f2087c98