Have Document::markers() return a reference

Source/web/WebViewImpl.cpp

 /*
  * Copyright (C) 2011, 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 3148 matching lines @@
     m_page->dragController().performDrag(&dragData);
 
     m_dragOperation = WebDragOperationNone;
     m_currentDragData = nullptr;
 }
 
 void WebViewImpl::spellingMarkers(WebVector<uint32_t>* markers)
 {
     Vector<uint32_t> result;
     for (LocalFrame* frame = m_page->mainFrame(); frame; frame = frame->tree().traverseNext()) {
-        const Vector<DocumentMarker*>& documentMarkers = frame->document()->markers()->markers();
+        const Vector<DocumentMarker*>& documentMarkers = frame->document()->markers().markers();
         for (size_t i = 0; i < documentMarkers.size(); ++i)
             result.append(documentMarkers[i]->hash());
     }
     markers->assign(result);
 }
 
 WebDragOperation WebViewImpl::dragTargetDragEnterOrOver(const WebPoint& clientPoint, const WebPoint& screenPoint, DragAction dragAction, int keyModifiers)
 {
     ASSERT(m_currentDragData);
 
@@ skipping 802 matching lines @@
     const PageScaleConstraints& constraints = m_pageScaleConstraintsSet.pageDefinedConstraints();
 
     if (!mainFrameImpl() || !mainFrameImpl()->frameView())
         return false;
 
     return mainFrameImpl()->frameView()->layoutSize().width() == m_size.width
         || (constraints.minimumScale == constraints.maximumScale && constraints.minimumScale != -1);
 }
 
 } // namespace blink