Migrate WTF::Deque::append() to ::push_back()

third_party/WebKit/Source/core/editing/commands/UndoStack.cpp

Index: third_party/WebKit/Source/core/editing/commands/UndoStack.cpp
diff --git a/third_party/WebKit/Source/core/editing/commands/UndoStack.cpp b/third_party/WebKit/Source/core/editing/commands/UndoStack.cpp
index eb9bf25f0bcb29018f84a5d89b8f832066d6dffb..51de7da95da2d8c65569c7103e14d2349ca876ff 100644
--- a/third_party/WebKit/Source/core/editing/commands/UndoStack.cpp
+++ b/third_party/WebKit/Source/core/editing/commands/UndoStack.cpp
@@ -51,11 +51,11 @@ void UndoStack::registerUndoStep(UndoStep* step) {
     m_undoStack.removeFirst();  // drop oldest item off the far end
   if (!m_inRedo)
     m_redoStack.clear();
-  m_undoStack.append(step);
+  m_undoStack.push_back(step);
 }
 
 void UndoStack::registerRedoStep(UndoStep* step) {
-  m_redoStack.append(step);
+  m_redoStack.push_back(step);
 }
 
 bool UndoStack::canUndo() const {