Simple CL to add a joinWithPossiblyEmptyArg to SkRect

include/core/SkRect.h

Index: include/core/SkRect.h
diff --git a/include/core/SkRect.h b/include/core/SkRect.h
index 0f68825fc1ced755a9ae41e89f807c9fcd76ff3b..fe276e6710b0d242a0b96de66eb22d87f7e7c015 100644
--- a/include/core/SkRect.h
+++ b/include/core/SkRect.h
@@ -747,14 +747,22 @@ public:
         if (fLeft >= fRight || fTop >= fBottom) {
             *this = r;
         } else {
-            fLeft   = SkMinScalar(fLeft, r.left());
-            fTop    = SkMinScalar(fTop, r.top());
-            fRight  = SkMaxScalar(fRight, r.right());
-            fBottom = SkMaxScalar(fBottom, r.bottom());
+            this->joinPossiblyEmptyRect(r);
         }
     }
 
     /**
+     * Joins the rectangle with another without checking if either are empty (may produce unexpected
+     * results if either rect is inverted).
+     */
+    void joinPossiblyEmptyRect(const SkRect& r) {
+        fLeft   = SkMinScalar(fLeft, r.left());
+        fTop    = SkMinScalar(fTop, r.top());
+        fRight  = SkMaxScalar(fRight, r.right());
+        fBottom = SkMaxScalar(fBottom, r.bottom());
+    }
+
+    /**
      *  Grow the rect to include the specified (x,y). After this call, the
      *  following will be true: fLeft <= x <= fRight && fTop <= y <= fBottom.
      *