Reland: Oilpan: Fix compile failure from r189762

Fixed non-Oilpan branch compile error.
We should use Vector<enum>, not a HeapVector<enum>

BUG=445292
TBR=oilpan-reviews

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=189769

Review URL: https://codereview.chromium.org/909763002

git-svn-id: svn://svn.chromium.org/blink/trunk@189772 bbb929c8-8fbe-4397-9dbb-9b2b20218538
3 files changed