OK, I'll take this too...

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/ef8ba7e30cc8392bb48ad021e59d3aa496c930f1

commit ef8ba7e30cc8392bb48ad021e59d3aa496c930f1
Author: svillar <svillar@igalia.com>
Date: Sat Jul 23 09:34:52 2016

[css-grid] grid-auto-flow|row should take a <track-size>+

Both properties were traditionally accepting just one <track-size> but
a recent change in the spec allows authors to pass a non-empty list of track
sizes. The first implicit track will use the first track size the second
implicit track will use the second track size and so on. For implicit tracks
before the explicit grid we need to transpose the order, i.e, the first
implicit track before the explicit grid will take the last track size.

Updated parsing, styling and track size resolution to support a list of
track sizes instead of just one. The grid shorthand was also updated as it
can set the value of the two grid-auto-* properties.

BUG= 618970 

Review-Url: https://codereview.chromium.org/2166393002
Cr-Commit-Position: refs/heads/master@{#407361}

[modify] https://crrev.com/ef8ba7e30cc8392bb48ad021e59d3aa496c930f1/third_party/WebKit/LayoutTests/fast/css-grid-layout/grid-auto-columns-rows-get-set-expected.txt
[modify] https://crrev.com/ef8ba7e30cc8392bb48ad021e59d3aa496c930f1/third_party/WebKit/LayoutTests/fast/css-grid-layout/grid-auto-columns-rows-get-set.html
[modify] https://crrev.com/ef8ba7e30cc8392bb48ad021e59d3aa496c930f1/third_party/WebKit/LayoutTests/fast/css-grid-layout/grid-shorthand-get-set-expected.txt
[modify] https://crrev.com/ef8ba7e30cc8392bb48ad021e59d3aa496c930f1/third_party/WebKit/LayoutTests/fast/css-grid-layout/grid-shorthand-get-set.html
[modify] https://crrev.com/ef8ba7e30cc8392bb48ad021e59d3aa496c930f1/third_party/WebKit/Source/core/css/CSSProperties.in
[modify] https://crrev.com/ef8ba7e30cc8392bb48ad021e59d3aa496c930f1/third_party/WebKit/Source/core/css/ComputedStyleCSSValueMapping.cpp
[modify] https://crrev.com/ef8ba7e30cc8392bb48ad021e59d3aa496c930f1/third_party/WebKit/Source/core/css/parser/CSSPropertyParser.cpp
[modify] https://crrev.com/ef8ba7e30cc8392bb48ad021e59d3aa496c930f1/third_party/WebKit/Source/core/css/resolver/StyleBuilderConverter.cpp
[modify] https://crrev.com/ef8ba7e30cc8392bb48ad021e59d3aa496c930f1/third_party/WebKit/Source/core/css/resolver/StyleBuilderConverter.h
[modify] https://crrev.com/ef8ba7e30cc8392bb48ad021e59d3aa496c930f1/third_party/WebKit/Source/core/layout/LayoutGrid.cpp
[modify] https://crrev.com/ef8ba7e30cc8392bb48ad021e59d3aa496c930f1/third_party/WebKit/Source/core/style/ComputedStyle.cpp
[modify] https://crrev.com/ef8ba7e30cc8392bb48ad021e59d3aa496c930f1/third_party/WebKit/Source/core/style/ComputedStyle.h
[modify] https://crrev.com/ef8ba7e30cc8392bb48ad021e59d3aa496c930f1/third_party/WebKit/Source/core/style/StyleGridData.h

Closing...