Add variable falling-out-of-scope case to SkVM trace tests.
Add variable falling-out-of-scope case to SkVM trace tests.

We didn't have any test cases where a loop variable (other than a loop
induction variable) fell out of scope. Now we have a demonstration of
the trouble behavior.

Change-Id: Iec070748c93aaeab1dc41a46c42e33c78b73d7f5
Bug: skia:12741
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/484560
Auto-Submit: John Stiles <f4fcf42d3bb5924557f1eeb3be66747535e585da@google.com>
Reviewed-by: Brian Osman <794c0b5534edf5601d88e1d41975d0262da12894@google.com>
Commit-Queue: John Stiles <f4fcf42d3bb5924557f1eeb3be66747535e585da@google.com>

aosp-mirror/platform_external_skia,google/skia,google/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,google/skia,google/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,google/skia,google/skia,google/skia,aosp-mirror/platform_external_skia