Invalidate filters like everything else

filters had a lot of custom code to generate their
invalidations. That was because they wanted to
invalidate all the composited layers up to the root.

It turns out that the composited layer walk seems
unneeded. For the accelerated filter case, it's
because cc stores the raw pixels and applies the
filters as needed. For the software case, I am
not totally convinced this is correct but the new
cases hitting such cases are passing so I am
willing a try as it removes a lot of complexity.

This change also removes some now unneeded logic
(hasSoftwareFilters and requiresFullLayerImageForFilters).

Review URL: https://codereview.chromium.org/465373004

git-svn-id: svn://svn.chromium.org/blink/trunk@181377 bbb929c8-8fbe-4397-9dbb-9b2b20218538