Add `SkIRect bounds()` convenience method to SkImageInfo and SkBitmap.

gm/texturedomaineffect.cpp

Index: gm/texturedomaineffect.cpp
diff --git a/gm/texturedomaineffect.cpp b/gm/texturedomaineffect.cpp
index acf039513db0ab0be6beb72b8a4596a3d3b53e0a..d235f7f86bc10a427d1fb473a17d103b48c0c0fc 100644
--- a/gm/texturedomaineffect.cpp
+++ b/gm/texturedomaineffect.cpp
@@ -105,15 +105,14 @@ protected:
         textureMatrices.back().preRotate(45.f, texture->width() / 2.f, texture->height() / 2.f);
 
         const SkIRect texelDomains[] = {
-            SkIRect::MakeWH(fBmp.width(), fBmp.height()),
+            fBmp.bounds(),
             SkIRect::MakeXYWH(fBmp.width() / 4,
                               fBmp.height() / 4,
                               fBmp.width() / 2,
                               fBmp.height() / 2),
         };
 
-        SkRect renderRect = SkRect::MakeWH(SkIntToScalar(fBmp.width()),
-                                           SkIntToScalar(fBmp.height()));
+        SkRect renderRect = SkRect::Make(fBmp.bounds());
         renderRect.outset(kDrawPad, kDrawPad);
 
         SkScalar y = kDrawPad + kTestPad;