mapRect should not fiddle with nonfinite values.

Docs-Preview: https://skia.org/?cl=128682
Bug: skia:7967
Change-Id: Ic43387b7705ee8385b8df2430886484ff856077c
Reviewed-on: https://skia-review.googlesource.com/128682
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Reed <reed@google.com>
11 files changed