Fix use-after-free discovered by fuzzer.

In cases where multiple variables were declared on a single line, it is
legal for variable initialization-expressions to reference variables
declared earlier in the var-decl statement. It is NOT legal for the
inliner to move those references up to the previous statement, where the
variable doesn't exist yet.

This is mitigated by disabling the IRGenerator inliner for var-decls
past the first one in a var-decls statement. (The optimizer will still
pass over this code later and is able to inline it correctly, if it is
worth doing.)

Change-Id: I7a0d45eab20e30ed9f6b2f5c1251b6e0d8eeaea3
Bug: oss-fuzz:26167
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/329357
Auto-Submit: John Stiles <johnstiles@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
5 files changed