Simplify conservative clip tracking for SkNoPixelsDevice

Deletes SkConservativeClip as a type, it was only used by
SkNoPixelsDevice at this point.

Simplifies the clip tracking to only rely on intersect/difference ops
(but also expands it to support updating overall bounds if the diff
op is a sufficiently large rectangle).

Adds SkRect::roundIn() -> SkIRect to match the exposed API for round()
and roundOut().

Bug: skia:10205
Change-Id: I1337a51a8a4e51f94fe2b5f9ab29a0b5058b8094
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/437737
Reviewed-by: Mike Reed <reed@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
5 files changed