Runtime effects: Detect calls to undefined functions

Previously, the CPU backend would catch this later (ByteCodeGenerator),
and the GPU backend would assert in expandFormatArgs (out-of-range
function index).

Change-Id: Ib84bf7c477ddcc9fd3091c5b106ebdd654e9a30b
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/276000
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
2 files changed