Rewrite NaN checks in terms of SkScalarIsNaN()

include/core/SkScalar.h

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkScalar_DEFINED
 #define SkScalar_DEFINED
 
@@ skipping 109 matching lines @@
 /** Returns true if x is not NaN and not infinite
  */
 static inline bool SkScalarIsFinite(SkScalar x) {
     // We rely on the following behavior of infinities and nans
     // 0 * finite --> 0
     // 0 * infinity --> NaN
     // 0 * NaN --> NaN
     SkScalar prod = x * 0;
     // At this point, prod will either be NaN or 0
     // Therefore we can return (prod == prod) or (0 == prod).
-    return prod == prod;
+    return !SkScalarIsNaN(prod);
 }
 
 /**
  *  Variant of SkScalarRoundToInt, that performs the rounding step (adding 0.5) explicitly using
  *  double, to avoid possibly losing the low bit(s) of the answer before calling floor().
  *
  *  This routine will likely be slower than SkScalarRoundToInt(), and should only be used when the
  *  extra precision is known to be valuable.
  *
  *  In particular, this catches the following case:
@@ skipping 100 matching lines @@
     SkASSERT(n >= 0);
     for (int i = 0; i < n; ++i) {
         if (a[i] != b[i]) {
             return false;
         }
     }
     return true;
 }
 
 #endif