Disallow narrowing conversions as part of matrix multiply-assignment

By doing the component-type deduction with simple multiplication:

  halfVec *= floatMat

Would decide that the resulting component type could be float, which
actually caused an assert later (because coerce() had to wrap the
variable reference in a Constructor, making it an invalid target for a
write).

Change-Id: I459897c62d80ecb1e406e5b351a80c25427d5a30
Bug: skia:10732
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/317587
Reviewed-by: John Stiles <johnstiles@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
1 file changed