The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b5be3c886b80b2a7b0db0714e2ae1a1cb154bf3d

commit b5be3c886b80b2a7b0db0714e2ae1a1cb154bf3d
Author: fs <fs@opera.com>
Date: Thu Sep 22 18:06:39 2016

Fix effect mapping computation for displacement-map w/ negative scale

When scale is negative, the displacement will be in the opposite
direction. Hence we need to only use the magnitude of the scale when
computing the effect of the filter.

BUG= 641854 

Review-Url: https://codereview.chromium.org/2359133003
Cr-Commit-Position: refs/heads/master@{#420396}

[add] https://crrev.com/b5be3c886b80b2a7b0db0714e2ae1a1cb154bf3d/third_party/WebKit/LayoutTests/css3/filters/effect-reference-displacement-negative-scale-expected.html
[add] https://crrev.com/b5be3c886b80b2a7b0db0714e2ae1a1cb154bf3d/third_party/WebKit/LayoutTests/css3/filters/effect-reference-displacement-negative-scale.html
[add] https://crrev.com/b5be3c886b80b2a7b0db0714e2ae1a1cb154bf3d/third_party/WebKit/LayoutTests/svg/filters/feDisplacementMap-negative-scale-expected.html
[add] https://crrev.com/b5be3c886b80b2a7b0db0714e2ae1a1cb154bf3d/third_party/WebKit/LayoutTests/svg/filters/feDisplacementMap-negative-scale.html
[modify] https://crrev.com/b5be3c886b80b2a7b0db0714e2ae1a1cb154bf3d/third_party/WebKit/Source/platform/graphics/filters/FEDisplacementMap.cpp