Fix cases of variable shadowing in /gm/.

If we manage to fix all the existing cases of variable shadowing, we
could enable -Wshadow.

Change-Id: I905459bf0bbaa205da7dc59e1910e345bed2af51
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/438538
Commit-Queue: John Stiles <johnstiles@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
diff --git a/gm/shadowutils.cpp b/gm/shadowutils.cpp
index 214027c..5364c08 100644
--- a/gm/shadowutils.cpp
+++ b/gm/shadowutils.cpp
@@ -91,9 +91,7 @@
     SkScalar dy = 0;
     SkTDArray<SkMatrix> matrices;
     matrices.push()->reset();
-    SkMatrix* m = matrices.push();
-    m->setRotate(33.f, 25.f, 25.f);
-    m->postScale(1.2f, 0.8f, 25.f, 25.f);
+    matrices.push()->setRotate(33.f, 25.f, 25.f).postScale(1.2f, 0.8f, 25.f, 25.f);
     for (auto& m : matrices) {
         for (int flags : { kNone_ShadowFlag, kTransparentOccluder_ShadowFlag }) {
             int pathCounter = 0;