Fix bounds of checking if a radii are too long for a side.

src/core/SkScaleToSides.h

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkScaleToSides_DEFINED
 #define SkScaleToSides_DEFINED
 
 #include <cmath>
 #include "SkScalar.h"
 #include "SkTypes.h"
 
 class ScaleToSides {
 public:
-    // This code assumes that a and b fit in in a float, and therefore the resulting smaller value
+    // This code assumes that a and b fit in a float, and therefore the resulting smaller value
     // of a and b will fit in a float. The side of the rectangle may be larger than a float.
     // Scale must be less than or equal to the ratio limit / (*a + *b).
     // This code assumes that NaN and Inf are never passed in.
     static void AdjustRadii(double limit, double scale, SkScalar* a, SkScalar* b) {
         SkASSERTF(scale < 1.0 && scale > 0.0, "scale: %g", scale);
 
         *a = (float)((double)*a * scale);
         *b = (float)((double)*b * scale);
 
-        // This check is conservative. (double)*a + (double)*b >= (double)(*a + *b)
-        if ((double)*a + (double)*b > limit) {
+        if (*a + *b > limit) {
             float* minRadius = a;
             float* maxRadius = b;
 
             // Force minRadius to be the smaller of the two.
             if (*minRadius > *maxRadius) {
                 SkTSwap(minRadius, maxRadius);
             }
 
             // newMinRadius must be float in order to give the actual value of the radius.
             // The newMinRadius will always be smaller than limit. The largest that minRadius can be
             // is 1/2 the ratio of minRadius : (minRadius + maxRadius), therefore in the resulting
             // division, minRadius can be no larger than 1/2 limit + ULP.
             float newMinRadius = *minRadius;
 
             // Because newMaxRadius is the result of a double to float conversion, it can be larger
             // than limit, but only by one ULP.
             float newMaxRadius = (float)(limit - newMinRadius);
 
             // If newMaxRadius forces the total over the limit, then it needs to be
             // reduced by one ULP to be less than limit - newMinRadius.
             // Note: nexttowardf is a c99 call and should be std::nexttoward, but this is not
             // implemented in the ARM compiler.
-            if ((double)newMaxRadius + (double)newMinRadius > limit) {
+            if (newMaxRadius + newMinRadius > limit) {
                 newMaxRadius = nexttowardf(newMaxRadius, 0.0);
             }
             *maxRadius = newMaxRadius;
         }
 
-        SkASSERTF(*a >= 0.0f && *b >= 0.0f, "a: %g, b: %g", *a, *b);
-        SkASSERTF((*a + *b) <= limit, "limit: %g, a: %g, b: %g", limit, *a, *b);
+        SkASSERTF(*a >= 0.0f && *b >= 0.0f, "a: %g, b: %g, limit: %g, scale: %g", *a, *b, limit,
+                  scale);
+        SkASSERTF(*a + *b <= limit, "\nlimit: %.10f, a: %.10f, b: %.10f, scale: %.20f",
+                  limit, *a, *b, scale);
     }
 };
 #endif // ScaleToSides_DEFINED