Make sure that inherit or initial works for unprefixed properties.

inherit and initial as values for a property are catched early in the
parser and it was not using the code to add unprefixed/prefixed automatically
as part of the declared style which is what is used later for style resolution.

This patch adds tests for transitions, animations and transforms.

BUG=368956

Review URL: https://codereview.chromium.org/268153002

git-svn-id: svn://svn.chromium.org/blink/trunk@173388 bbb929c8-8fbe-4397-9dbb-9b2b20218538