Disable several plugin tests while the test plugin is fixed.

BUG=363099,371084
TBR=mkwst@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/659013002

git-svn-id: svn://svn.chromium.org/blink/trunk@183789 bbb929c8-8fbe-4397-9dbb-9b2b20218538