This CL adds tests for the else statement AST node.
Bug: tint:11
Change-Id: I30c024775d188223d5a3875ee973ffc8ac78c645
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/16466
Reviewed-by: Sarah Mashayekhi <sarahmashay@google.com>
Commit-Queue: Sarah Mashayekhi <sarahmashay@google.com>