[CSS Shapes] Remove deprecated shapes

Remove support for deprecated shape types and syntax. These have already been removed from the CSS Shapes specification, so this aligns the implementation with the specification.
    
The "new" tests below were simply moved from the old csswg directory, as they were the only tests there that applied to the current syntax.

Cheery-pick from http://trac.webkit.org/changeset/165472
BUG=354159

Review URL: https://codereview.chromium.org/200633005

git-svn-id: svn://svn.chromium.org/blink/trunk@169688 bbb929c8-8fbe-4397-9dbb-9b2b20218538