Make InterpolationEnvironment virutal

third_party/WebKit/Source/core/animation/SVGLengthListInterpolationType.cpp

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/animation/SVGLengthListInterpolationType.h"
 
-#include "core/animation/InterpolationEnvironment.h"
+#include <memory>
+#include "core/animation/SVGInterpolationEnvironment.h"
 #include "core/animation/SVGLengthInterpolationType.h"
 #include "core/animation/UnderlyingLengthChecker.h"
 #include "core/svg/SVGLengthList.h"
-#include <memory>
 
 namespace blink {
 
 InterpolationValue SVGLengthListInterpolationType::MaybeConvertNeutral(
     const InterpolationValue& underlying,
     ConversionCheckers& conversion_checkers) const {
   size_t underlying_length =
       UnderlyingLengthChecker::GetUnderlyingLength(underlying);
   conversion_checkers.push_back(
       UnderlyingLengthChecker::Create(underlying_length));
@@ skipping 56 matching lines @@
     const NonInterpolableValue*) const {
   NOTREACHED();
   // This function is no longer called, because apply has been overridden.
   return nullptr;
 }
 
 void SVGLengthListInterpolationType::Apply(
     const InterpolableValue& interpolable_value,
     const NonInterpolableValue* non_interpolable_value,
     InterpolationEnvironment& environment) const {
-  SVGElement& element = environment.SvgElement();
+  SVGElement& element = ToSVGInterpolationEnvironment(environment).SvgElement();
   SVGLengthContext length_context(&element);
 
   SVGLengthList* result = SVGLengthList::Create(unit_mode_);
   const InterpolableList& list = ToInterpolableList(interpolable_value);
   for (size_t i = 0; i < list.length(); i++) {
     result->Append(SVGLengthInterpolationType::ResolveInterpolableSVGLength(
         *list.Get(i), length_context, unit_mode_, negative_values_forbidden_));
   }
 
   element.SetWebAnimatedAttribute(Attribute(), result);
 }
 
 }  // namespace blink