Remove scroll-position-restored-on-back-at-load-event in LeakExpectation

scroll-position-restored-on-back-at-load-event was fixed in
crrev.com/c/207e8662.

Bug: 835802
Change-Id: Ic69c2844799d8aa7e2c57c4f952c36fd986b6cee
Reviewed-on: https://chromium-review.googlesource.com/1089588Reviewed-by: David Bokan <bokan@chromium.org>
Commit-Queue: Jianpeng Chao <chaopeng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#565299}

third_party/WebKit/LayoutTests/LeakExpectations

@@ -71,7 +71,6 @@ crbug.com/821547 [ Linux ] virtual/threaded/animations/interpolation/filter-inte
 # -----------------------------------------------------------------
 # Sheriff 2018-04-23
 # -----------------------------------------------------------------
-crbug.com/835802 [ Linux ] fast/loader/scroll-position-restored-on-back-at-load-event.html [ Pass Leak ]
 crbug.com/836278 [ Linux ] external/wpt/offscreen-canvas/convert-to-blob/offscreencanvas.convert.to.blob.html [ Pass Leak ]
 crbug.com/836278 [ Linux ] virtual/threaded/external/wpt/offscreen-canvas/convert-to-blob/offscreencanvas.convert.to.blob.html [ Pass Leak ]