Web Animations API: Fix Synthetic keyframes + partial keyframes

Source/core/animation/KeyframeEffectModel.cpp

Index: Source/core/animation/KeyframeEffectModel.cpp
diff --git a/Source/core/animation/KeyframeEffectModel.cpp b/Source/core/animation/KeyframeEffectModel.cpp
index b6f813f8ada431190082cdb48cad2f8ada85ca79..860452c01879ecefb52197031b3a2f187d688745 100644
--- a/Source/core/animation/KeyframeEffectModel.cpp
+++ b/Source/core/animation/KeyframeEffectModel.cpp
@@ -205,6 +205,7 @@ void KeyframeEffectModel::ensureKeyframeGroups() const
             else
                 group = groupIter->value.get();
 
+            ASSERT(keyframe->composite() == AnimationEffect::CompositeReplace);
             group->appendKeyframe(adoptPtr(
                 new PropertySpecificKeyframe(keyframe->offset(), keyframe->easing(), keyframe->propertyValue(property), keyframe->composite())));
         }
@@ -247,7 +248,6 @@ KeyframeEffectModel::PropertySpecificKeyframe::PropertySpecificKeyframe(double o
     : m_offset(offset)
     , m_easing(easing)
 {
-    ASSERT(composite == AnimationEffect::CompositeReplace);
     m_value = AnimatableValue::takeConstRef(value);

[shans, 2014/03/19 09:06:20]

Store composite in an m_composite member variable of the
PropertySpecificKeyframe

 }
 
@@ -293,21 +293,10 @@ void KeyframeEffectModel::PropertySpecificKeyframeGroup::removeRedundantKeyframe
 void KeyframeEffectModel::PropertySpecificKeyframeGroup::addSyntheticKeyframeIfRequired()
 {
     ASSERT(!m_keyframes.isEmpty());
-    double offset = m_keyframes.first()->offset();
-    bool allOffsetsEqual = true;
-    for (PropertySpecificKeyframeVector::const_iterator iter = m_keyframes.begin() + 1; iter != m_keyframes.end(); ++iter) {
-        if ((*iter)->offset() != offset) {
-            allOffsetsEqual = false;
-            break;
-        }
-    }
-    if (!allOffsetsEqual)
-        return;
-
-    if (!offset)
-        appendKeyframe(m_keyframes.first()->cloneWithOffset(1.0));
-    else
-        m_keyframes.insert(0, adoptPtr(new PropertySpecificKeyframe(0.0, nullptr, AnimatableValue::neutralValue(), CompositeAdd)));
+    if (m_keyframes.first()->offset() != 0.0)
+        m_keyframes.insert(0, adoptPtr(new PropertySpecificKeyframe(0, nullptr, AnimatableValue::neutralValue(), CompositeAdd)));
+    if (m_keyframes.last()->offset() != 1.0)
+        appendKeyframe(adoptPtr(new PropertySpecificKeyframe(1, nullptr, AnimatableValue::neutralValue(), CompositeAdd)));
 }
 
 void KeyframeEffectModel::trace(Visitor* visitor)