Don't use post multiplication on transforms with compatible pairs of operations

third_party/WebKit/Source/platform/transforms/TransformOperations.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 34 matching lines @@
     if (*m_operations[i] != *o.m_operations[i])
       return false;
   }
 
   return true;
 }
 
 bool TransformOperations::operationsMatch(
     const TransformOperations& other) const {
   size_t numOperations = operations().size();
-  // If the sizes of the function lists don't match, the lists don't match
   if (numOperations != other.operations().size())
     return false;
 
-  // If the types of each function are not the same, the lists don't match
   for (size_t i = 0; i < numOperations; ++i) {
-    if (!operations()[i]->isSameType(*other.operations()[i]))
+    if (operations()[i]->primitiveType() !=
+        other.operations()[i]->primitiveType()) {
       return false;
+    }
   }
   return true;
 }
 
 TransformOperations TransformOperations::blendByMatchingOperations(
     const TransformOperations& from,
     const double& progress) const {
   TransformOperations result;
 
   unsigned fromSize = from.operations().size();
@@ skipping 35 matching lines @@
   // Evaluate blended matrix here to avoid creating a nested data structure of
   // unbounded depth.
   TransformationMatrix fromTransform;
   TransformationMatrix toTransform;
   from.apply(FloatSize(), fromTransform);
   apply(FloatSize(), toTransform);
   toTransform.blend(fromTransform, progress);
   return Matrix3DTransformOperation::create(toTransform);
 }
 
+// https://drafts.csswg.org/css-transforms-1/#interpolation-of-transforms
 TransformOperations TransformOperations::blend(const TransformOperations& from,
                                                double progress) const {
   if (from == *this || (!from.size() && !size()))
     return *this;
 
   // If either list is empty, use blendByMatchingOperations which has special
   // logic for this case.
   if (!from.size() || !size() || from.operationsMatch(*this))
     return blendByMatchingOperations(from, progress);
 
@@ skipping 300 matching lines @@
 }
 
 TransformOperations TransformOperations::zoom(double factor) const {
   TransformOperations result;
   for (auto& transformOperation : m_operations)
     result.m_operations.append(transformOperation->zoom(factor));
   return result;
 }
 
 }  // namespace blink