Revert "In SkCanvas destructor, discard (rather than blit) unbalanced layers"

This reverts commit 879b2f2e6ebd7fb465c0679e22c48a0cae58c61e.

Reason for revert: UAF

Original change's description:
> In SkCanvas destructor, discard (rather than blit) unbalanced layers
>
> Bug: skia:12267
> Change-Id: I6808f62b2385a3466b1a93db905041a6529f58cb
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/433360
> Commit-Queue: Brian Osman <brianosman@google.com>
> Reviewed-by: Florin Malita <fmalita@google.com>
> Reviewed-by: Brian Salomon <bsalomon@google.com>
> Reviewed-by: Mike Reed <reed@google.com>

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: skia:12267
Change-Id: I616e6c65c1eb3b6d3f67b2dde6be3db4de6db18a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/438739
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
2 files changed