Change SkImageFilter's cropRect from SkIRect to a CropRect struct

include/core/SkRect.h

Index: include/core/SkRect.h
diff --git a/include/core/SkRect.h b/include/core/SkRect.h
index d8919ae5d6b888d3195cc57ce7346bc905cf2a8c..c615603d7e85b1d7adb645c20390a402f0c8f908 100644
--- a/include/core/SkRect.h
+++ b/include/core/SkRect.h
@@ -371,6 +371,12 @@ struct SK_API SkRect {
         return r;
     }
 
+    static SkRect SK_WARN_UNUSED_RESULT MakeLargest() {
+        SkRect r;
+        r.setLargest();
+        return r;
+    }
+
     static SkRect SK_WARN_UNUSED_RESULT MakeWH(SkScalar w, SkScalar h) {
         SkRect r;
         r.set(0, 0, w, h);
@@ -419,6 +425,11 @@ struct SK_API SkRect {
      */
     bool isEmpty() const { return fLeft >= fRight || fTop >= fBottom; }
 
+    bool isLargest() const { return SK_ScalarMin == fLeft &&
+                                    SK_ScalarMin == fTop &&
+                                    SK_ScalarMax == fRight &&
+                                    SK_ScalarMax == fBottom; }
+
     /**
      *  Returns true iff all values in the rect are finite. If any are
      *  infinite or NaN (or SK_FixedNaN when SkScalar is fixed) then this