Note the report that this only occurs on low DPI machines.

https://codereview.chromium.org/2869813002/

If 'will-change: transform' is used in the test case, Safari has the same problem.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/fca776d5b4979b1f9d86926bfb6d3fb14a0343f3

commit fca776d5b4979b1f9d86926bfb6d3fb14a0343f3
Author: yigu <yigu@chromium.org>
Date: Fri May 12 01:04:12 2017

Fix the bug that absolute positioned element moves unexpectedly

For an absolute positioned element, if its containing block is the body
it's not supposed to move as scroll. However, on low dpi devices, it
doesn't get composited if its ancestor is isolated composited therefore
it moves unexpectedly.

BUG= 719533 
TEST=third_party/WebKit/LayoutTests/compositing/overflow/absolute-element-in-isolated-composited-ancestor.html
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Review-Url: https://codereview.chromium.org/2869813002
Cr-Commit-Position: refs/heads/master@{#471158}

[modify] https://crrev.com/fca776d5b4979b1f9d86926bfb6d3fb14a0343f3/third_party/WebKit/LayoutTests/TestExpectations
[add] https://crrev.com/fca776d5b4979b1f9d86926bfb6d3fb14a0343f3/third_party/WebKit/LayoutTests/compositing/overflow/absolute-element-in-isolated-composited-ancestor-expected.html
[add] https://crrev.com/fca776d5b4979b1f9d86926bfb6d3fb14a0343f3/third_party/WebKit/LayoutTests/compositing/overflow/absolute-element-in-isolated-composited-ancestor.html
[modify] https://crrev.com/fca776d5b4979b1f9d86926bfb6d3fb14a0343f3/third_party/WebKit/LayoutTests/compositing/overflow/nested-render-surfaces-with-intervening-clip-expected.png
[modify] https://crrev.com/fca776d5b4979b1f9d86926bfb6d3fb14a0343f3/third_party/WebKit/Source/core/layout/compositing/CompositingReasonFinder.cpp

Note that the fix works without SPV2 enabled.