CSS Properties & Values API: Support <resolution> values

This patch adds support for <resolution>-typed registered properties.
We already parse the string '<resolution>', so this patch just adds the
logic to parse the actual <resolution> values.

BUG=641877

Review-Url: https://codereview.chromium.org/2618553003
Cr-Commit-Position: refs/heads/master@{#441795}
5 files changed