Implement caching of stroked paths in the tessellating path renderer.

This requires adding the stroke info to the cache key, and doing the
stroking and dashing before rendering as triangles.

BUG=skia:3755

Committed: https://skia.googlesource.com/skia/+/29e0d3f267a03546f236023347cdb4595ece2fd1

Review URL: https://codereview.chromium.org/1275553002
diff --git a/include/gpu/GrTestUtils.h b/include/gpu/GrTestUtils.h
index 6fed7e1..91f36ea 100644
--- a/include/gpu/GrTestUtils.h
+++ b/include/gpu/GrTestUtils.h
@@ -16,6 +16,7 @@
 #include "SkRandom.h"
 #include "SkStrokeRec.h"
 
+class GrStrokeInfo;
 class SkMatrix;
 class SkPath;
 class SkRRect;
@@ -35,6 +36,7 @@
 const SkPath& TestPath(SkRandom*);
 const SkPath& TestPathConvex(SkRandom*);
 SkStrokeRec TestStrokeRec(SkRandom*);
+GrStrokeInfo TestStrokeInfo(SkRandom*);
 
 }