Enable Oilpan by default in modules/speech/

R=dmazzoni@chromium.org,haraken@chromium.org,tommi@chromium.org,tkent@chromium.org
BUG=340522

Review URL: https://codereview.chromium.org/315133004

git-svn-id: svn://svn.chromium.org/blink/trunk@175872 bbb929c8-8fbe-4397-9dbb-9b2b20218538