The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/163b3f0ee31cf076a6a128fc8a84ba82956d58d1

commit 163b3f0ee31cf076a6a128fc8a84ba82956d58d1
Author: Eric Willigers <ericwilligers@chromium.org>
Date: Sat Oct 21 02:37:59 2017

CSS: Use counter for negative brightness filter

filter's brightness() function currently accepts negative values.
This contradicts the spec:

https://drafts.fxtf.org/filter-effects/#FilterProperty
brightness() = brightness( <number-percentage> )
Negative values are not allowed.

Add use counter to guide decision on updating the implementation or
spec.

BUG= 776276 

Change-Id: Ie0e911505e066c8e0499395203bfbb468b454274
Reviewed-on: https://chromium-review.googlesource.com/727388
Reviewed-by: Rick Byers <rbyers@chromium.org>
Reviewed-by: nainar <nainar@chromium.org>
Commit-Queue: Eric Willigers <ericwilligers@chromium.org>
Cr-Commit-Position: refs/heads/master@{#510646}
[add] https://crrev.com/163b3f0ee31cf076a6a128fc8a84ba82956d58d1/third_party/WebKit/LayoutTests/css3/filters/usecounter-negative-brightness-number.html
[add] https://crrev.com/163b3f0ee31cf076a6a128fc8a84ba82956d58d1/third_party/WebKit/LayoutTests/css3/filters/usecounter-negative-brightness-percentage.html
[modify] https://crrev.com/163b3f0ee31cf076a6a128fc8a84ba82956d58d1/third_party/WebKit/Source/core/css/parser/CSSPropertyParserHelpers.cpp
[modify] https://crrev.com/163b3f0ee31cf076a6a128fc8a84ba82956d58d1/third_party/WebKit/public/platform/web_feature.mojom
[modify] https://crrev.com/163b3f0ee31cf076a6a128fc8a84ba82956d58d1/tools/metrics/histograms/enums.xml