Update a result vector when sampling animation effects.

Source/core/animation/InterpolationEffect.cpp

Index: Source/core/animation/InterpolationEffect.cpp
diff --git a/Source/core/animation/InterpolationEffect.cpp b/Source/core/animation/InterpolationEffect.cpp
index b2db74a1a4f98f348a282cb3abe4aa17bbf80564..900036a06ec18d6dda6413ecf4d5f34793178e3f 100644
--- a/Source/core/animation/InterpolationEffect.cpp
+++ b/Source/core/animation/InterpolationEffect.cpp
@@ -7,10 +7,13 @@
 
 namespace blink {
 
-PassOwnPtrWillBeRawPtr<WillBeHeapVector<RefPtrWillBeMember<Interpolation> > > InterpolationEffect::getActiveInterpolations(double fraction, double iterationDuration) const
+void InterpolationEffect::getActiveInterpolations(double fraction, double iterationDuration, OwnPtrWillBeRawPtr<WillBeHeapVector<RefPtrWillBeMember<Interpolation>>>& result) const
 {
+    if (!result)
+        result = adoptPtrWillBeNoop(new WillBeHeapVector<RefPtrWillBeMember<Interpolation> >());
 
-    WillBeHeapVector<RefPtrWillBeMember<Interpolation> >* result = new WillBeHeapVector<RefPtrWillBeMember<Interpolation> >();
+    size_t existingSize = result->size();
+    size_t resultIndex = 0;
 
     for (size_t i = 0; i < m_interpolations.size(); ++i) {
         const InterpolationRecord* record = m_interpolations[i].get();
@@ -20,11 +23,14 @@ PassOwnPtrWillBeRawPtr<WillBeHeapVector<RefPtrWillBeMember<Interpolation> > > In
             if (record->m_easing)
                 localFraction = record->m_easing->evaluate(localFraction, accuracyForDuration(iterationDuration));
             interpolation->interpolate(0, localFraction);
-            result->append(interpolation);
+            if (resultIndex < existingSize)
+                (*result)[resultIndex++] = interpolation;
+            else
+                result->append(interpolation);
         }
     }
-
-    return adoptPtrWillBeNoop(result);
+    if (resultIndex < existingSize)
+        result->shrink(resultIndex);
 }
 
 void InterpolationEffect::InterpolationRecord::trace(Visitor* visitor)