Removing the -webkit prefix from CSS Shapes tests

Layout tests should use the new, unprefixed CSS Shapes properties.

BUG=307652

Review URL: https://codereview.chromium.org/38653003

git-svn-id: svn://svn.chromium.org/blink/trunk@160750 bbb929c8-8fbe-4397-9dbb-9b2b20218538