Delete now-unnecessary hack for 0-size layers, now that we use transformOrigin
instead of anchorPoint.

The hack is no longer necessary because transformOrigin is an additive offset,
as opposed to a multiplicative one.

BUG=372837

Review URL: https://codereview.chromium.org/329553003

git-svn-id: svn://svn.chromium.org/blink/trunk@175911 bbb929c8-8fbe-4397-9dbb-9b2b20218538