Remove AT::blend, TM::isBackFaceVisible, and FloatPolygon::overlapsRect

This patch removes the following dead math code:
1) AffineTransform::blend
2) TransformationMatrix::isBackFaceVisible - removed in wkrev.com/145442
3) FloatPolygon::overlapsRect

No tests as there is no change in behavior.

Review URL: https://codereview.chromium.org/438123002

git-svn-id: svn://svn.chromium.org/blink/trunk@179758 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Drop const_iterator for AttributeCollection

Drop const_iterator for AttributeCollection and use iterator instead as it is
equivalent. AttributeCollection::iterator is inherently const, while
MutableAttributeCollection::iterator isn't.

Since here the constness is defined by the collection type (AttributeCollection
vs MutableAttributeCollection), I don't think we need to distinguish iterator
vs const_iterator. Using iterator everywhere also makes the code a bit shorter.

R=adamk@chromium.org, esprehn@chromium.org

Review URL: https://codereview.chromium.org/448043003

git-svn-id: svn://svn.chromium.org/blink/trunk@179760 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Auto-rebaseline for r179749

http://src.chromium.org/viewvc/blink?view=revision&revision=179749

TBR=abarth@chromium.org

Review URL: https://codereview.chromium.org/448313002

git-svn-id: svn://svn.chromium.org/blink/trunk@179761 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Allow paint invalidation containers to cross frame boundaries.

Previously, the *actual* paint invalidation container, meaning the enclosing
compositing layer / root RenderView, could already have been across a frame boundary. The logic to do this correctly was done via special code in RenderView.

Instead, generalize the existing mechanisms to find a paint invalidation container
and map rects to repaint container coordinate space to cross frame boundaries.
This simplifies the code, and also causes paint invalidation rects to always be stored
in the coordinate space of their graphics layer backing. The latter is important if we want
to use these rects for determining which parts of a graphics layer need to be painted.

BUG=401156

Review URL: https://codereview.chromium.org/445793002

git-svn-id: svn://svn.chromium.org/blink/trunk@179762 bbb929c8-8fbe-4397-9dbb-9b2b20218538