[css-logical] Implement flow-relative margin, padding and border shorthand properties

They are implemented behind the CSSLogical runtime flag.

Intent to Implement:
https://groups.google.com/a/chromium.org/forum/#!msg/blink-dev/48OwfwZrbvI/A1XZFGkzAwAJ

Spec: https://drafts.csswg.org/css-logical/#box

BUG=850004

TEST=external/wpt/css/css-logical/logical-box-border-shorthands.html
TEST=external/wpt/css/css-logical/logical-box-border-color.html
TEST=external/wpt/css/css-logical/logical-box-border-style.html
TEST=external/wpt/css/css-logical/logical-box-border-width.html
TEST=external/wpt/css/css-logical/logical-box-margin.html
TEST=external/wpt/css/css-logical/logical-box-padding.html

The tests still have some failures because sideways writing modes have
not been implemented yet (http://crbug.com/680331).

Change-Id: Ibe3d7f39e1ce17de465aa635388b3f8510ed82a3
Reviewed-on: https://chromium-review.googlesource.com/1122872
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Manuel Rego Casasnovas <rego@igalia.com>
Reviewed-by: Anders Ruud <andruud@chromium.org>
Commit-Queue: Oriol Brufau <obrufau@igalia.com>
Cr-Commit-Position: refs/heads/master@{#572576}
38 files changed