Make SkMatrix::get*Scale[s]() fail on NaN

include/core/SkMatrix.h

Index: include/core/SkMatrix.h
diff --git a/include/core/SkMatrix.h b/include/core/SkMatrix.h
index 97a53505ef3734ae36de8d5e0799b07d4c4e075a..0ebe3280e2180778fa6fa32564baf1fe401d5ee0 100644
--- a/include/core/SkMatrix.h
+++ b/include/core/SkMatrix.h
@@ -635,15 +635,17 @@ public:
 
     /**
      * Calculates the minimum scaling factor of the matrix as computed from the SVD of the upper
-     * left 2x2. If the matrix has perspective -1 is returned.
+     * left 2x2. If the max scale factor cannot be computed (for example overflow or perspective)
+     * -1 is returned.
      *
-     * @return minumum scale factor
+     * @return minimum scale factor
      */
     SkScalar getMinScale() const;
 
     /**
      * Calculates the maximum scaling factor of the matrix as computed from the SVD of the upper
-     * left 2x2. If the matrix has perspective -1 is returned.
+     * left 2x2. If the max scale factor cannot be computed (for example overflow or perspective)
+     * -1 is returned.
      *
      * @return maximum scale factor
      */
@@ -651,10 +653,10 @@ public:
 
     /**
      * Gets both the min and max scale factors. The min scale factor is scaleFactors[0] and the max
-     * is scaleFactors[1]. If the matrix has perspective false will be returned and scaleFactors
-     * will be unchanged.
+     * is scaleFactors[1]. If the min/max scale factors cannot be computed false is returned and the
+     * values of scaleFactors[] are undefined.
      */
-    bool getMinMaxScales(SkScalar scaleFactors[2]) const;
+    bool SK_WARN_UNUSED_RESULT getMinMaxScales(SkScalar scaleFactors[2]) const;
 
     /**
      *  Attempt to decompose this matrix into a scale-only component and whatever remains, where