Remove unused TransformOperation::isIdentity

Source/platform/transforms/TransformOperation.h

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2003, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *
  * 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
@@ skipping 39 matching lines @@
         Perspective,
         Interpolated,
         Identity, None
     };
 
     virtual ~TransformOperation() { }
 
     virtual bool operator==(const TransformOperation&) const = 0;
     bool operator!=(const TransformOperation& o) const { return !(*this == o); }
 
-    virtual bool isIdentity() const = 0;
-
     virtual void apply(TransformationMatrix&, const FloatSize& borderBoxSize) const = 0;
 
     virtual PassRefPtr<TransformOperation> blend(const TransformOperation* from, double progress, bool blendToIdentity = false) = 0;
 
     virtual OperationType type() const = 0;
     bool isSameType(const TransformOperation& other) const { return other.type() == type(); }
     virtual bool canBlendWith(const TransformOperation& other) const = 0;
 
     bool is3DOperation() const
     {
         OperationType opType = type();
         return opType == ScaleZ
             || opType == Scale3D
             || opType == TranslateZ
             || opType == Translate3D
             || opType == RotateX
             || opType == RotateY
             || opType == Rotate3D
             || opType == Matrix3D
             || opType == Perspective
             || opType == Interpolated;
     }
 
     virtual bool dependsOnBoxSize() const { return false; }
 };
 
 } // namespace blink
 
 #endif // TransformOperation_h