Do scaling for oversized filters in the deferred case.

The legacy filters path adjusts for oversized filters by scaling
them to fit a maximum of 16 MPixels. Do the same for the deferred
path.

Tests: svg/filters/big-sized-filter-2.svg after
https://codereview.chromium.org/340203002/ lands and rolls in.

R=fmalita@chromium.org
BUG=386733

Review URL: https://codereview.chromium.org/346893004

git-svn-id: svn://svn.chromium.org/blink/trunk@176561 bbb929c8-8fbe-4397-9dbb-9b2b20218538