Revert "Add geometric implementation for ambient shadows"

This reverts commit fdb1bdf1aa4e7f14befcb3acc3f586e7734190ea.

Reason for revert: Breaking the roll (see e.g. https://codereview.chromium.org/2652833006)

Original change's description:
> Add geometric implementation for ambient shadows
> 
> BUG=skia:6119
> 
> Change-Id: I3140522f223c35fc059a33b593064897485dff7c
> Reviewed-on: https://skia-review.googlesource.com/7273
> Reviewed-by: Brian Salomon <bsalomon@google.com>
> Commit-Queue: Jim Van Verth <jvanverth@google.com>
> 

TBR=jvanverth@google.com,bsalomon@google.com,robertphillips@google.com,reviews@skia.org,reed@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:6119

Change-Id: I307f6084c40e5ba305c38d15b6b433465295553c
Reviewed-on: https://skia-review.googlesource.com/7480
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
6 files changed