Oilpan: Prepare to move SQLTransactionWrapper and CangeVersionWrapper to Oilpan heap.

They should be GarbageCollectedFinalized because ChangeVersionWrapper has an
OwnPtr member.

BUG=347902

Review URL: https://codereview.chromium.org/211933005

git-svn-id: svn://svn.chromium.org/blink/trunk@170001 bbb929c8-8fbe-4397-9dbb-9b2b20218538