Fix tests for rect() function on clip property.
Fix circle() shape function tests and add new tests. Remove rectangle() tests after removing rectangle() from the spec.
Fix and add new ellipse() shape tests. Fix descriptions for polygon() shape tests.
Merge pull request #615 from dirkschulze/css-masking-clip-fix

Fix tests for rect() function on clip property.
Merge pull request #616 from dirkschulze/clip-path-fixes-1

Fix circle() shape function tests and add new tests. Remove rectangle() ...
Merge pull request #617 from dirkschulze/clip-path-fixes-2

Fix and add new ellipse() shape tests. Fix descriptions for polygon() sh...