Revert "Update GrCircleBlurFragmentProcessor to use a child FP."

This reverts commit 88c6539a3f4b9f97918e9c58e92a19984b667609.

Reason for revert: reduction in precision causes blocky blur effect on some GPUs (different order of casting in rewritten expression)

Original change's description:
> Update GrCircleBlurFragmentProcessor to use a child FP.
> 
> We are updating FPs to receive their input via a child FP where
> possible, instead of relying on the input color.
> 
> Change-Id: If7c42e556aff3464ec0392f362c97c2e8c6ff91d
> Bug: skia:10217
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/294258
> Reviewed-by: Michael Ludwig <michaelludwig@google.com>
> Commit-Queue: John Stiles <johnstiles@google.com>

TBR=michaelludwig@google.com,johnstiles@google.com

Change-Id: I24a7493f71caa2d9da4de568671f637707d05040
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: skia:10217
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/295438
Reviewed-by: John Stiles <johnstiles@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
4 files changed