[LayoutNG] Label its own bug number for...

[LayoutNG] Label its own bug number for compositing/layer-creation/stacking-context-overlap-nested.html

TBR=atotic@chromium.org
NOTRY=true

Bug: 869265
Cq-Include-Trybots: luci.chromium.try:linux_layout_tests_layout_ng
Change-Id: I9a87e971df42fcef062344aae8a9bc34e7171ffd
Reviewed-on: https://chromium-review.googlesource.com/1156116
Commit-Queue: Koji Ishii <kojii@chromium.org>
Reviewed-by: Koji Ishii <kojii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#579318}

third_party/WebKit/LayoutTests/FlagExpectations/enable-blink-features=LayoutNG

@@ -62,7 +62,7 @@ crbug.com/591099 fast/dom/inner-text-first-letter.html [ Pass ]
 crbug.com/591099 animations/rotate-transform-equivalent.html [ Failure ]
 crbug.com/728378 compositing/culling/tile-occlusion-boundaries.html [ Failure ]
 crbug.com/591099 compositing/iframes/floating-self-painting-frame.html [ Failure Pass ]
-crbug.com/591099 compositing/layer-creation/stacking-context-overlap-nested.html [ Failure ]
+crbug.com/869265 compositing/layer-creation/stacking-context-overlap-nested.html [ Failure ]
 crbug.com/591099 compositing/perpendicular-layer-sorting.html [ Failure Pass ]
 crbug.com/591099 compositing/squashing/squash-above-fixed-3.html [ Failure Pass ]
 crbug.com/591099 compositing/squashing/squash-same-transform-ancestor.html [ Failure Pass ]