We weren't allocating uniform storage until after the first update, far
too late for users to pump uniform values in. They're now allocated as
soon as the effect is created, which is tested by the new GM.
Change-Id: Ia0084bcec5986479c350ead27d14344c3ed82520
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/362176
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
964b4465c4