Remove unused variable 'heapIndex'
Remove unused variable 'heapIndex'

Bug: NA

Though we set this variable, we never use its value. This causes a
warning in Android.

Change-Id: I84492fd97e8c6f23db7bf51c116d227551ae7a94
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/469358
Commit-Queue: Leon Scroggins <995cad867ca30d6399abe011583a53547c8afea1@google.com>
Commit-Queue: Greg Daniel <39df0a804564ccb6cf75f18db79653821f37c1c5@google.com>
Auto-Submit: Leon Scroggins <995cad867ca30d6399abe011583a53547c8afea1@google.com>
Reviewed-by: Greg Daniel <39df0a804564ccb6cf75f18db79653821f37c1c5@google.com>

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