Fix common axes logic to detect negated axes as not common

third_party/WebKit/Source/platform/transforms/Rotation.cpp

 /*
  * Copyright (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 64 matching lines @@
     resultAngleB = b.angle;
     return true;
   }
 
   if (isZeroB) {
     resultAxis = a.axis;
     resultAngleA = a.angle;
     return true;
   }
 
+  double dot = a.axis.dot(b.axis);
+  if (dot < 0)
+    return false;
+
   double aSquared = a.axis.lengthSquared();
   double bSquared = b.axis.lengthSquared();
-  double dot = a.axis.dot(b.axis);
   double error = std::abs(1 - (dot * dot) / (aSquared * bSquared));
   if (error > kAngleEpsilon)
     return false;
 
   resultAxis = a.axis;
   resultAngleA = a.angle;
   resultAngleB = b.angle;
   return true;
 }
 
@@ skipping 21 matching lines @@
   if (getCommonAxis(a, b, axis, angleA, angleB))
     return Rotation(axis, angleA + angleB);
 
   TransformationMatrix matrix;
   matrix.rotate3d(a);
   matrix.rotate3d(b);
   return extractFromMatrix(matrix, b);
 }
 
 }  // namespace blink