Fix mime-type of layout tests

git-svn-id: svn://svn.chromium.org/blink/trunk@173472 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Oilpan: Use HeapListHashSet for IDBTransaction::m_requestList.

BUG=366528

Review URL: https://codereview.chromium.org/269353002

git-svn-id: svn://svn.chromium.org/blink/trunk@173473 bbb929c8-8fbe-4397-9dbb-9b2b20218538