Gardening: Many of focus-by-mouse tests are not flaky now.
Gardening: Many of focus-by-mouse tests are not flaky now.

BUG=254332
TBR=keishi@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/34233002

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@160124 bbb929c8-8fbe-4397-9dbb-9b2b20218538

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