Blink Animation: Extend Animation's GC lifetime if it has a finish promise.

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

Index: third_party/WebKit/Source/core/animation/Animation.cpp
diff --git a/third_party/WebKit/Source/core/animation/Animation.cpp b/third_party/WebKit/Source/core/animation/Animation.cpp
index a65c0b78df8b14bdd0c9e46510832eab27dc8582..bc2efd8eca3daa7d561485734bfec104ea498ca0 100644
--- a/third_party/WebKit/Source/core/animation/Animation.cpp
+++ b/third_party/WebKit/Source/core/animation/Animation.cpp
@@ -651,7 +651,11 @@ ExecutionContext* Animation::getExecutionContext() const {
 }
 
 bool Animation::hasPendingActivity() const {
-  return m_pendingFinishedEvent ||
+  bool hasPendingPromise =
+      !m_finished && m_finishedPromise &&
+      m_finishedPromise->getState() == ScriptPromisePropertyBase::Pending;
+
+  return m_pendingFinishedEvent || hasPendingPromise ||
          (!m_finished && hasEventListeners(EventTypeNames::finish));
 }