The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/aa8304925672de76f13fcd46d49f305d98e636b6

commit aa8304925672de76f13fcd46d49f305d98e636b6
Author: Chris Nardi <cnardi@chromium.org>
Date: Tue Apr 03 03:00:01 2018

Serialize font shorthand like any other shorthand

The font shorthand had a short-circuit in StylePropertySerializer, which
meant that it was never serialized as a shorthand for style.cssText,
citing reasons of web incompatibility. However, it appears that all
other major browsers serialize font as a shorthand instead of having
style.cssText expand to all properties. Remove this short-circuit to
match other browsers.

Bug:  827921 
Change-Id: I4d522b41a6153808b6b8dab17831afdd8315fdc3
Reviewed-on: https://chromium-review.googlesource.com/989834
Commit-Queue: Chris Nardi <cnardi@chromium.org>
Reviewed-by: Timothy Loh <timloh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#547607}
[add] https://crrev.com/aa8304925672de76f13fcd46d49f305d98e636b6/third_party/WebKit/LayoutTests/external/wpt/css/cssom/font-shorthand-serialization.html
[modify] https://crrev.com/aa8304925672de76f13fcd46d49f305d98e636b6/third_party/WebKit/LayoutTests/external/wpt/css/cssom/serialize-variable-reference-expected.txt
[modify] https://crrev.com/aa8304925672de76f13fcd46d49f305d98e636b6/third_party/WebKit/LayoutTests/external/wpt/css/cssom/serialize-variable-reference.html
[modify] https://crrev.com/aa8304925672de76f13fcd46d49f305d98e636b6/third_party/WebKit/LayoutTests/http/tests/devtools/console/console-format-style-whitelist-expected.txt
[modify] https://crrev.com/aa8304925672de76f13fcd46d49f305d98e636b6/third_party/WebKit/Source/core/css/StylePropertySerializer.cpp