Remove passing root-layer-scrolls TestExpectation

fast/events/scale-and-scroll-iframe-window.html was fixed in r533170 but
the TestExpectation line wasn't removed to avoid interfering with
landing r533694. Dashboard says it's been passing reliably.

Bug: 781431
Change-Id: I92ff5c63246fd68556598a42b09e86477e983cdd
Reviewed-on: https://chromium-review.googlesource.com/899644
Commit-Queue: David Bokan <bokan@chromium.org>
Reviewed-by: Steve Kobes <skobes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#534735}

third_party/WebKit/LayoutTests/TestExpectations

@@ -3296,7 +3296,6 @@ crbug.com/417782 compositing/visibility/visibility-image-layers-dynamic.html [ F
 crbug.com/417782 css3/filters/effect-reference-subregion-nested.html [ Failure ]
 crbug.com/417782 fast/css/sticky/replaced-sticky.html [ Failure ]
 crbug.com/417782 fast/css/sticky/sticky-style-change.html [ Failure ]
-crbug.com/417782 fast/events/scale-and-scroll-iframe-window.html [ Failure ]
 crbug.com/417782 fast/frames/iframe-scaling-with-scroll.html [ Failure ]
 crbug.com/417782 fast/overflow/scrollRevealButton.html [ Failure ]
 crbug.com/417782 fast/scroll-behavior/scroll-into-view-sticky.html [ Crash ]
@@ -3329,7 +3328,6 @@ crbug.com/417782 [ Linux ] virtual/android/fullscreen/compositor-touch-hit-rects
 crbug.com/417782 [ Linux ] virtual/android/fullscreen/full-screen-iframe-allowed-video.html [ Failure ]
 crbug.com/417782 [ Linux ] virtual/android/fullscreen/video-controls-timeline.html [ Failure ]
 crbug.com/417782 [ Linux ] virtual/android/fullscreen/video-scrolled-iframe.html [ Failure ]
-crbug.com/417782 virtual/mouseevent_fractional/fast/events/scale-and-scroll-iframe-window.html [ Failure ]
 crbug.com/417782 virtual/prefer_compositing_to_lcd_text/compositing/overflow/tiled-mask.html [ Failure ]
 crbug.com/417782 virtual/scroll_customization/fast/events/touch/compositor-touch-hit-rects-iframes.html [ Failure ]
 crbug.com/417782 virtual/scroll_customization/fast/scroll-behavior/scroll-into-view-sticky.html [ Crash ]