Migrate the remaining CSS properties interpolable as Lengths to LengthInterpolationType

Source/core/animation/LengthInterpolationType.h

Index: Source/core/animation/LengthInterpolationType.h
diff --git a/Source/core/animation/LengthInterpolationType.h b/Source/core/animation/LengthInterpolationType.h
index c743794a3a0d660cb8fd4e662176b9a61cba7e37..64bb35204e07624dc496d1599d4ef871e6910a05 100644
--- a/Source/core/animation/LengthInterpolationType.h
+++ b/Source/core/animation/LengthInterpolationType.h
@@ -10,6 +10,8 @@
 
 namespace blink {
 
+class ComputedStyle;
+
 class LengthInterpolationType : public InterpolationType {
 public:
     LengthInterpolationType(CSSPropertyID);
@@ -18,6 +20,8 @@ public:
     void apply(const InterpolableValue&, const NonInterpolableValue*, StyleResolverState&) const final;
 
 private:
+    float effectiveZoom(const ComputedStyle&) const;
+
     PassOwnPtr<InterpolationValue> maybeConvertLength(const Length&, float zoom) const;
     PassOwnPtr<InterpolationValue> maybeConvertNeutral() const final;
     PassOwnPtr<InterpolationValue> maybeConvertInitial() const final;