Move shapes tests to their own directory

With the split in the CSS Exclusions and Shapes specifications, it no
longer makes sense to house the CSS Shapes tests under the exclusions
directory. This patch moves the Shapes tests to their own directory
under fast/shapes. Some small adjustments were necessary in tests or
utilities that were involved in both shapes and exclusions testing, but
for the most part this patch just moves files.

BUG=248304

Review URL: https://chromiumcodereview.appspot.com/19850002

git-svn-id: svn://svn.chromium.org/blink/trunk@154877 bbb929c8-8fbe-4397-9dbb-9b2b20218538