Change signatures of filter bounds methods to return a rect.

Change filterBounds(), onFilterBounds() and onFilterNodeBounds() and computeFastBounds() to
return the destination rectangle. There was no code path that could
return false, and returning rects by value is ok now.

BUG=skia:5094
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1823573003

Review URL: https://codereview.chromium.org/1823573003
28 files changed