Improves filter paint rectangles.

This patch improves the calculation of filter paint rectangles by using
the areas actually needed by the following filters, as well as the regions
that actually have data, to determine the processing rects. This lets us
apply restrictions for some composite operations, which improves
performance significantly in some scenarios (e.g. blend modes overlay,
hardlight and difference in Swiffy).

The calculation is done by requesting the painting area from the last
effect, which intersects it for its effect rectangle and propagates an
inflated request (to adjust for any expansion done by the effect) to its
inputs. This propagates downward until we reach a source effect
(SourceGraphic/Alpha or feImage) where we can use the repaint rectangle
of the source to restrict the region. The restricted region then bubbles
upward, again adjusted for any expansion/offset done by the effects and
intersected by max effect rectangle. In the special case of 'in' and
'atop' compositing the paint areas can be further restricted.

Also fixes incorrect effect region of 'in' composites and failure to apply
the correct color space in feFlood when the primitive is redrawn (caught
by svg/dynamic-updates/SVGFECompositeElement-dom-operator-attr.html,
unable to reproduce as a standalone testcase).

BUG=331751

Review URL: https://codereview.chromium.org/123823003

git-svn-id: svn://svn.chromium.org/blink/trunk@164682 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Add autofill preview support for Textarea

BUG=314976
R=isherman@chromium.org

Review URL: https://codereview.chromium.org/120443003

git-svn-id: svn://svn.chromium.org/blink/trunk@164683 bbb929c8-8fbe-4397-9dbb-9b2b20218538