Move implementation of Keyframe::PropertySpecificKeyframe to keyframe.cc

ATM Keyframe::PropertySpecificKeyframe::PropertySpecificKeyframe is
implemented in keyframe_effect_model.cc, not keyframe.cc. Move it there
for better readability.

Change-Id: I5f103d03e6c8bc658a486dc4a9cdb3011adb6050
Reviewed-on: https://chromium-review.googlesource.com/1101476Reviewed-by: Stephen McGruer <smcgruer@chromium.org>
Commit-Queue: Yi Gu <yigu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#567415}

third_party/blink/renderer/core/animation/keyframe.cc

@@ -10,6 +10,16 @@
 
 namespace blink {
 
+Keyframe::PropertySpecificKeyframe::PropertySpecificKeyframe(
+    double offset,
+    scoped_refptr<TimingFunction> easing,
+    EffectModel::CompositeOperation composite)
+    : offset_(offset), easing_(std::move(easing)), composite_(composite) {
+  DCHECK(!IsNull(offset));
+  if (!easing_)
+    easing_ = LinearTimingFunction::Shared();
+}
+
 scoped_refptr<Interpolation>
 Keyframe::PropertySpecificKeyframe::CreateInterpolation(
     const PropertyHandle& property_handle,

third_party/blink/renderer/core/animation/keyframe_effect_model.cc

@@ -319,16 +319,6 @@ bool KeyframeEffectModelBase::IsReplaceOnly() const {
   return true;
 }
 
-Keyframe::PropertySpecificKeyframe::PropertySpecificKeyframe(
-    double offset,
-    scoped_refptr<TimingFunction> easing,
-    EffectModel::CompositeOperation composite)
-    : offset_(offset), easing_(std::move(easing)), composite_(composite) {
-  DCHECK(!IsNull(offset));
-  if (!easing_)
-    easing_ = LinearTimingFunction::Shared();
-}
-
 void KeyframeEffectModelBase::PropertySpecificKeyframeGroup::AppendKeyframe(
     scoped_refptr<Keyframe::PropertySpecificKeyframe> keyframe) {
   DCHECK(keyframes_.IsEmpty() ||