Fix reverse bounds calculation for SkImageFilters::Compose

Since reverse bounds calculation is more-or-less the inverse operation
of forward bounds calculation, it needs to be computed from the outer
filter and then the inner filter. Previously bounds were always
computed from inner and then outer, which is only valid for forward
bounds calculations.

Bug: skia:10888
Change-Id: I94a2170617ed01c8ec3066f3518c6baa06da952d
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/337401
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
2 files changed