slightly simplify skvm interpreter asserts
slightly simplify skvm interpreter asserts

No need to check the condition twice.

This really just makes it easier to find the code that handles
Op::assert in the interpreter more easily... it's the code that uses the
only two vptest instructions (four before this CL).

Change-Id: I890a2e224515d766b29d41ba07ef6f639e6387d8
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/317424
Reviewed-by: Mike Klein <14574f09dfa9b4e14759b88c3426a495a0e627b0@google.com>
Commit-Queue: Mike Klein <14574f09dfa9b4e14759b88c3426a495a0e627b0@google.com>

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