[svg] Implement onObjectBoundingBox for circle and path

Also removed an erroneous call to mapToRect() when returning bounds
for SkSVGContainer. The contexts in which we access object bounds are
always such that any transforms have already been applied.

Change-Id: Ieac488e1699d3ebff56038d6ada36737291671eb
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/345117
Commit-Queue: Tyler Denniston <tdenniston@google.com>
Reviewed-by: Florin Malita <fmalita@chromium.org>
diff --git a/modules/svg/include/SkSVGPath.h b/modules/svg/include/SkSVGPath.h
index 979fe8a..7723bfd 100644
--- a/modules/svg/include/SkSVGPath.h
+++ b/modules/svg/include/SkSVGPath.h
@@ -25,6 +25,8 @@
 
     SkPath onAsPath(const SkSVGRenderContext&) const override;
 
+    SkRect onObjectBoundingBox(const SkSVGRenderContext&) const override;
+
 private:
     SkSVGPath();