Adding three flaky tests found by FindIt

NOTRY=true
TBR=dmazzoni@chromium.org

Here are the findit links:

https://findit-for-me.appspot.com/waterfall/flake?key=ag9zfmZpbmRpdC1mb3ItbWVy5gELEhdNYXN0ZXJGbGFrZUFuYWx5c2lzUm9vdCKvAWNocm9taXVtLndlYmtpdC9XZWJLaXQgTGludXggVHJ1c3R5IExlYWsvMjU3NzAvd2Via2l0X2xheW91dF90ZXN0cy9kbWx5ZEhWaGJDOTBhSEpsWVdSbFpDOW1ZWE4wTDNOamNtOXNiQzFpWldoaGRtbHZjaTl6Ylc5dmRHZ3RjMk55YjJ4c0wzTmpjbTlzYkMxa2RYSnBibWN0YzJWc1pXTjBhVzl1TG1oMGJXdz0MCxITTWFzdGVyRmxha2VBbmFseXNpcxgBDA

https://findit-for-me.appspot.com/waterfall/flake?key=ag9zfmZpbmRpdC1mb3ItbWVyxQELEhdNYXN0ZXJGbGFrZUFuYWx5c2lzUm9vdCKOAWNocm9taXVtLmxpbnV4L0xpbnV4IFRlc3RzIChkYmcpKDEpLzc1Mjk1L3dlYmtpdF9sYXlvdXRfdGVzdHMvZG1seWRIVmhiQzkwYUhKbFlXUmxaQzltWVhOMEwzTmpjbTlzYkdsdVp5OXVieTFvYjNabGNpMWtkWEpwYm1jdGMyTnliMnhzTG1oMGJXdz0MCxITTWFzdGVyRmxha2VBbmFseXNpcxgBDA

https://findit-for-me.appspot.com/waterfall/flake?key=ag9zfmZpbmRpdC1mb3ItbWVy4QELEhdNYXN0ZXJGbGFrZUFuYWx5c2lzUm9vdCKqAWNocm9taXVtLmxpbnV4L0xpbnV4IFRlc3RzIChkYmcpKDEpLzc1Mjk1L3dlYmtpdF9sYXlvdXRfdGVzdHMvZG1seWRIVmhiQzltY21GamRHbHZibUZzWDNOamNtOXNiR2x1WjE5MGFISmxZV1JsWkM5bVlYTjBMM05qY205c2JHbHVaeTl1Ynkxb2IzWmxjaTFrZFhKcGJtY3RjMk55YjJ4c0xtaDBiV3c9DAsSE01hc3RlckZsYWtlQW5hbHlzaXMYAQw

Bug: 899347
Change-Id: I8c0acfa91d22845c6020e4544c853b16bf85a712
Reviewed-on: https://chromium-review.googlesource.com/c/1302819Reviewed-by: Mason Freed <masonfreed@chromium.org>
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Commit-Queue: Mason Freed <masonfreed@chromium.org>
Commit-Queue: Dominic Mazzoni <dmazzoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#603199}

third_party/WebKit/LayoutTests/TestExpectations

@@ -103,7 +103,10 @@ crbug.com/891427 virtual/threaded/synthetic_gestures/animated-wheel-tiny-delta.h
 crbug.com/891427 virtual/threaded/synthetic_gestures/smooth-scroll-tiny-delta.html [ Pass Failure Timeout Crash ]
 # Next 1 here: https://ci.chromium.org/p/chromium/builders/luci.chromium.try/mac10.12-blink-rel/1427
 crbug.com/891427 virtual/threaded/synthetic_gestures/synthetic-pinch-zoom-gesture-touchpad-zoom-out-slow.html [ Pass Failure Timeout Crash ]
-
+# Adding three more found by findit:
+crbug.com/891427 virtual/threaded/fast/scroll-behavior/smooth-scroll/scroll-during-selection.html [ Pass Failure Timeout Crash ]
+crbug.com/891427 virtual/threaded/fast/scrolling/no-hover-during-scroll.html [ Pass Failure Timeout Crash ]
+crbug.com/891427 virtual/fractional_scrolling_threaded/fast/scrolling/no-hover-during-scroll.html [ Pass Failure Timeout Crash ]
 
 # Remove these when --enable-display-compositor-pixel-dump becomes the
 # "default" setting. These will all need to be re-baselined at that point.