Blink gardneing, updated test expectations.

BUG=355459
TBR=apavlov

Review URL: https://codereview.chromium.org/209683003

git-svn-id: svn://svn.chromium.org/blink/trunk@169824 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Check toWebPluginContainerImpl() result before dereferencing, even with isPluginDocument() sometimes it's 0;

BUG=331927

Review URL: https://codereview.chromium.org/207143003

git-svn-id: svn://svn.chromium.org/blink/trunk@169825 bbb929c8-8fbe-4397-9dbb-9b2b20218538