Stop requiring RTAdjust var when it is an interface block field
Stop requiring RTAdjust var when it is an interface block field

We were previously relying on the RTAdjust var's (essentially
meaningless in that case) value being non-null even when RTAdjust was
an interface block field instead of a var. This breaks runtime effects
built by the DSLParser, which does not set RTAdjust unless there's
actually an RTAdjust var.

Change-Id: I0938e1562ebf997af7b1f4dd9beb60fcd7909a20
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/445096
Reviewed-by: John Stiles <f4fcf42d3bb5924557f1eeb3be66747535e585da@google.com>
Commit-Queue: Ethan Nicholas <d2cfb8c2f603266f4dc3a6f09acbcc0089603b37@google.com>

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