Unskip 'http/tests/security/cross-frame-access-put.html'

This test is broken on Windows, as 'window.screenTop' and 'window.screenX'
return unexpected values. Since the exact value is completely irrelevant to
the test, this patch updates the test to ignore the actual value, and
simply verify that it correctly matches its cross-frame counterpart.

This allows us to merge the platform-specific results, and unskip the test
on Windows. Huzzah.

BUG=260218
R=jochen@chromium.org

Review URL: https://chromiumcodereview.appspot.com/19163002

git-svn-id: svn://svn.chromium.org/blink/trunk@154216 bbb929c8-8fbe-4397-9dbb-9b2b20218538