Revert "Allow null rect for saveLayer"

This reverts commit f2e9709266bb7d3f5777dbba1d99970ff8423962.

Reason for revert: Breaking the build

Original change's description:
> Allow null rect for saveLayer
> 
> Bug: skia:10043
> Change-Id: Ia049e72565810e1f72500141678e166027230535
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/277097
> Reviewed-by: Kevin Lubick <kjlubick@google.com>

TBR=kjlubick@google.com,dnfield@google.com

Change-Id: I0aae159380cbdfd4ead0f8e3e9c9de284c2dc103
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: skia:10043
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/277182
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Commit-Queue: Kevin Lubick <kjlubick@google.com>
3 files changed