Simplify common case for recttorect

Change-Id: I70e295a677b8cac3d578e3cd57472c833af03877
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/354336
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Mike Reed <reed@google.com>
diff --git a/samplecode/SampleHT.cpp b/samplecode/SampleHT.cpp
index 940cd2f..5547b31 100644
--- a/samplecode/SampleHT.cpp
+++ b/samplecode/SampleHT.cpp
@@ -31,10 +31,7 @@
 }
 
 static bool oval_contains(const SkRect& r, SkScalar x, SkScalar y) {
-    SkMatrix m;
-    m.setRectToRect(r, gUnitSquare, SkMatrix::kFill_ScaleToFit);
-    SkPoint pt;
-    m.mapXY(x, y, &pt);
+    SkPoint pt = SkMatrix::RectToRect(r, gUnitSquare).mapXY(x, y);
     return SkPointPriv::LengthSqd(pt) <= 1;
 }