Remove getComputedStyle(e).css* properties

Having deprecated the getComputedStyle(e).css* properties, this patch
removes the capability completely. Affected tests are updated (and the
deprecation-specific test is removed), and the UseCounter is removed
since it is no longer needed.

BUG=413205

Review URL: https://codereview.chromium.org/1607653002

Cr-Commit-Position: refs/heads/master@{#370215}
9 files changed