Fix sprite blitter choice logic

While we're asking if there are any color space xform steps to do,
let's look at all 5 of them, including whether we need to unpremul or
premul.  The sprite blitter paths this logic guards can't handle
any change in color space _or_ alpha type, so this is a perfect fit.

Without this fix, we'd happily draw premul into unpremul using memcpy().
(Unpremul -> premul was already guarded by the check with my new note.)

Change-Id: Ic8d9e69f6c7bd2902ff77393de1da9cd940ea826
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/257657
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
1 file changed