Remove more testing of getPropertyCSSValue

As getPropertyCSSValue, CSSValue, CSSValueList, CSSPrimitiveValue,
Counter, RGBColor and Rect are no longer web-exposed, we should stop
testing them so we can delete the interface.

BUG=428595

Review URL: https://codereview.chromium.org/711473003

git-svn-id: svn://svn.chromium.org/blink/trunk@184975 bbb929c8-8fbe-4397-9dbb-9b2b20218538