Reland "Fix the fat rect bug in the threaded backend"

This reverts commit 1b637615144604a2d50cf983ac9aa5aab71cf73b.

Reason for revert: add guard flag

Original change's description:
> Revert "Fix the fat rect bug in the threaded backend"
> 
> This reverts commit c41569a29fde10c6fec43cc4593334e9a4b34b76.
> 
> Reason for revert: maybe break the Chrome layout tests
> 
> Original change's description:
> > Fix the fat rect bug in the threaded backend
> > 
> > Bug: skia:7813
> > Change-Id: I954232be1dccc63ce412ccde92c4f0e4617317b9
> > Reviewed-on: https://skia-review.googlesource.com/121641
> > Reviewed-by: Cary Clark <caryclark@google.com>
> > Commit-Queue: Yuqian Li <liyuqian@google.com>
> 
> TBR=caryclark@google.com,liyuqian@google.com,reed@google.com
> 
> Change-Id: If35617a9774b3367561981e39a2fa89a972684b9
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Bug: skia:7813
> Reviewed-on: https://skia-review.googlesource.com/121820
> Reviewed-by: Yuqian Li <liyuqian@google.com>
> Commit-Queue: Yuqian Li <liyuqian@google.com>

TBR=caryclark@google.com,liyuqian@google.com,reed@google.com

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: skia:7813
Change-Id: I8b17be4251b5efc20142295cca787474f32e3a86
Reviewed-on: https://skia-review.googlesource.com/122100
Commit-Queue: Yuqian Li <liyuqian@google.com>
Reviewed-by: Yuqian Li <liyuqian@google.com>
diff --git a/gm/aaa.cpp b/gm/aaa.cpp
index 910ce19..b2fc633 100644
--- a/gm/aaa.cpp
+++ b/gm/aaa.cpp
@@ -44,6 +44,7 @@
 
         y += 200;
 
+        canvas->save();
         canvas->translate(0, y);
         canvas->rotate(1);
         canvas->drawRect({ 20, 20, 20.2f, 200 }, p);
@@ -78,6 +79,7 @@
 
         // skbug.com/7573
         y += 200;
+        canvas->save();
         canvas->translate(0, y);
         p.setAntiAlias(true);
         path.reset();
@@ -87,6 +89,15 @@
         path.lineTo(1.93990216f, 10.5837256f);
         canvas->drawPath(path, p);
         canvas->restore();
+
+        // skbug.com/7813
+        // t8888 splits the 800-high canvas into 3 pieces; the boundary is close to 266 and 534
+        path.reset();
+        path.moveTo(700, 266);
+        path.lineTo(710, 266);
+        path.lineTo(710, 534);
+        path.lineTo(700, 534);
+        canvas->drawPath(path, p);
     }
 
 private: