Deprecate the currently used NGMarginStrut in favor of the new one.

This will deprecate NGMarginStrut and introduce the new NGMarginStrut with new interface.
See http://crrev.com/2597823004 for more details about how it will be used.

BUG=635619

Review-Url: https://codereview.chromium.org/2651853002
Cr-Commit-Position: refs/heads/master@{#445709}
11 files changed