Revert of Revert of allow canvas to force conservative clips (for speed) (patchset...

Revert of Revert of allow canvas to force conservative clips (for speed) (patchset #1 id:1 of https://codereview.chromium.org/554033003/)

Reason for revert:
May just rebaseline, plus want to see the results of the chrome tests, so re-trying this CL.

Original issue's description:
> Revert of allow canvas to force conservative clips (for speed) (patchset #7 id:120001 of https://codereview.chromium.org/541593005/)
>
> Reason for revert:
> multipicturedraw failed on nvprmsaa -- don't know why yet
>
> Original issue's description:
> > Allow SkCanvas to be initialized to force conservative rasterclips. This has the following effects:
> >
> > 1. Queries to the current clip will be conservatively large. This can mean the quickReject may return false more often.
> >
> > 2. The conservative clips mean less work is done.
> >
> > 3. Enabled by default for Gpu, Record, and NoSaveLayer canvases.
> >
> > 4. API is private for now.
> >
> > Committed: https://skia.googlesource.com/skia/+/27a5e656c3d6ef22f9cb34de18e1b960da3aa241
>
> TBR=robertphillips@google.com,bsalomon@google.com,mtklein@google.com,junov@google.com
> NOTREECHECKS=true
> NOTRY=true
>
> Committed: https://skia.googlesource.com/skia/+/6f09709519b79a1159f3826645f1c5fbc101ee11

R=robertphillips@google.com, bsalomon@google.com, mtklein@google.com, junov@google.com, reed@google.com
TBR=bsalomon@google.com, junov@google.com, mtklein@google.com, reed@google.com, robertphillips@google.com
NOTREECHECKS=true
NOTRY=true

Author: reed@chromium.org

Review URL: https://codereview.chromium.org/560713002