Remove tests which are only testing getPropertyCSSValue, etc.

getPropertyCSSValue, CSSValue, etc. are no longer exposed to the web.
This patch removes the tests which exist only to test this functionality.

BUG=428595

Review URL: https://codereview.chromium.org/689323002

git-svn-id: svn://svn.chromium.org/blink/trunk@184808 bbb929c8-8fbe-4397-9dbb-9b2b20218538