Allow using overrideContainingBlockContentLogical{Width,Height} outside of grid

I am using it for the LayoutNG transition; there does not seem to be a need
to limit this to grid items as nothing else currently sets this.

This change also makes LayoutNG use this new function.

R=eae@chromium.org,ikilpatrick@chromium.org,glebl@chromium.org
BUG=635619

Review-Url: https://codereview.chromium.org/2257223002
Cr-Commit-Position: refs/heads/master@{#413445}
2 files changed