Fix assertion when swizzling literals.

The fuzzer generated the expression `(6).xx`, which triggered a
type-checking assertion. This swizzle was otherwise harmless.

Change-Id: Icb12f93fe3f6d88265d67e689ceb85cf1085c9e8
Bug: oss-fuzz:36655
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/434464
Commit-Queue: John Stiles <johnstiles@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
2 files changed