Revert "Zero-initialize buffers used for SkMesh."

This reverts commit 8b3bcc102e3708769d59a6418335df99b37a5912.

Reason for revert: VK_WHOLE_SIZE busting chrome
 
Original change's description:
> Zero-initialize buffers used for SkMesh.
>
> Ensures applications don't draw using undefined buffer contents
>
> Bug: skia:12720
> Change-Id: I0add2297833fcf0eea4e2b7e7868a759f30c37b3
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/571420
> Reviewed-by: Greg Daniel <egdaniel@google.com>
> Commit-Queue: Brian Salomon <bsalomon@google.com>

Bug: skia:12720
Change-Id: I1ef52cffc0026e1901a21bb4bf70278d331f1756
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/572694
Commit-Queue: Brian Salomon <bsalomon@google.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
34 files changed