Some css-multicol tests are flaky

Examples of failed build https://uberchromegw.corp.google.com/i/chromium.win/builders/Win7%20Tests%20%28dbg%29%281%29/builds/65117
https://uberchromegw.corp.google.com/i/chromium.win/builders/Win7%20Tests%20%28dbg%29%281%29/builds/65113
https://uberchromegw.corp.google.com/i/chromium.win/builders/Win7%20Tests%20%28dbg%29%281%29/builds/65111

TBR=mstensho@chromium.org

Bug: 788337
Change-Id: Ie848524cd39c333dd96ecc55db0d133791768d1f
Reviewed-on: https://chromium-review.googlesource.com/817748
Commit-Queue: Maxim Kolosovskiy <kolos@chromium.org>
Reviewed-by: Maxim Kolosovskiy <kolos@chromium.org>
Cr-Commit-Position: refs/heads/master@{#523075}

third_party/WebKit/LayoutTests/TestExpectations

@@ -2425,7 +2425,7 @@ crbug.com/626703 [ Win ] external/wpt/css/css-ui/text-overflow-020.html [ Failur
 crbug.com/626703 [ Win ] external/wpt/css/css-writing-modes/box-offsets-rel-pos-vlr-005.xht [ Failure ]
 crbug.com/626703 [ Win ] external/wpt/css/css-writing-modes/box-offsets-rel-pos-vrl-004.xht [ Failure ]
 
-# css-multicol tests failing on initial import from web-platform-tests
+# css-multicol tests are failing or flaky on initial import from web-platform-tests
 crbug.com/788337 external/wpt/css/css-multicol/multicol-block-no-clip-001.xht [ Failure ]
 crbug.com/788337 external/wpt/css/css-multicol/multicol-block-no-clip-002.xht [ Failure ]
 crbug.com/788337 external/wpt/css/css-multicol/multicol-count-computed-003.xht [ Failure ]
@@ -2440,6 +2440,14 @@ crbug.com/788337 external/wpt/css/css-multicol/multicol-span-all-margin-nested-0
 crbug.com/788337 external/wpt/css/css-multicol/multicol-span-float-001.xht [ Failure ]
 crbug.com/788337 external/wpt/css/css-multicol/multicol-width-small-001.xht [ Failure ]
 crbug.com/788337 external/wpt/css/css-multicol/multicol-zero-height-001.xht [ Failure ]
+crbug.com/788337 external/wpt/css/css-multicol/multicol-fill-balance-001.xht [ Pass Failure ]
+crbug.com/788337 external/wpt/css/css-multicol/multicol-gap-negative-001.xht [ Pass Failure ]
+crbug.com/788337 external/wpt/css/css-multicol/multicol-overflow-000.xht [ Pass Failure ]
+crbug.com/788337 external/wpt/css/css-multicol/multicol-overflowing-001.xht [ Pass Failure ]
+crbug.com/788337 external/wpt/css/css-multicol/multicol-rule-002.xht [ Pass Failure ]
+crbug.com/788337 external/wpt/css/css-multicol/multicol-rule-shorthand-2.xht [ Pass Failure ]
+crbug.com/788337 external/wpt/css/css-multicol/multicol-rule-stacking-001.xht [ Pass Failure ]
+crbug.com/788337 external/wpt/css/css-multicol/multicol-width-001.xht [ Pass Failure ]
 
 # This test times out on debug builds, see https://crbug.com/755810
 crbug.com/626703 [ Debug ] external/wpt/html/semantics/tabular-data/processing-model-1/span-limits.html [ Skip ]