[CSS Shapes] Fix Shapes's polygon tests

Shapes's polygon tests didn't run because of a typo and some missing js include.

Merged revisions:
- #1 http://trac.webkit.org/changeset/153338
- #2 http://trac.webkit.org/changeset/153350

Review URL: https://chromiumcodereview.appspot.com/20489004

git-svn-id: svn://svn.chromium.org/blink/trunk@155102 bbb929c8-8fbe-4397-9dbb-9b2b20218538