[test] Speculatively skip some layout tests to fix OOM issue.

BUG=chromium:498689
LOG=n
NOTRY=true
TBR=sergiyb@chromium.org

Review URL: https://codereview.chromium.org/1179573003

Cr-Commit-Position: refs/heads/master@{#28915}

tools/blink_tests/TestExpectations

@@ -3,6 +3,6 @@
 # Turn off Slimming Paint tests on linux.
 [ Linux ] virtual/slimmingpaint/ [ Skip ]
 
-crbug.com/498689 [ Linux ] virtual/display_list_2d_canvas/canvas/philip/tests/2d.canvas.readonly.html [ Skip ]
-crbug.com/498689 [ Linux ] canvas/philip/tests/2d.canvas.readonly.html [ Skip ]
+crbug.com/498689 [ Linux ] virtual/display_list_2d_canvas/canvas/philip/tests/ [ Skip ]
+crbug.com/498689 [ Linux ] canvas/philip/tests/ [ Skip ]