Revert of Fix a memory leak when decoding corrupted indexed PNGs. (patchset #2 id...

Revert of Fix a memory leak when decoding corrupted indexed PNGs. (patchset #2 id:20001 of https://codereview.chromium.org/951663002/)

Reason for revert:
speculative revert due to many failures in tree

Original issue's description:
> Fix a memory leak when decoding corrupted indexed PNGs.
> Commit to branch refs/heads/png-leak
>
> BUG=skia:3457
>
> Committed: https://skia.googlesource.com/skia/+/561a1ca9559a1ea7589ab93350124284fcef3315

TBR=scroggo@google.com,dml@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:3457

Review URL: https://codereview.chromium.org/980203005