Cleanup: Start using toFoo methods as part of newly adopted coding guideline.

Source/core/dom/DocumentMarkerController.cpp

Index: Source/core/dom/DocumentMarkerController.cpp
diff --git a/Source/core/dom/DocumentMarkerController.cpp b/Source/core/dom/DocumentMarkerController.cpp
index 0682b64d971844063c2305a976fcfb79acb7c53b..48af00e18ef7cf6290a67b47ec43e092287e6f0f 100644
--- a/Source/core/dom/DocumentMarkerController.cpp
+++ b/Source/core/dom/DocumentMarkerController.cpp
@@ -114,7 +114,7 @@ void DocumentMarkerController::addTextMatchMarker(const Range* range, bool activ
             // matches off-screen are (that haven't been painted yet).
             Node* node = textPiece->startContainer();
             Vector<DocumentMarker*> markers = markersFor(node);
-            static_cast<RenderedDocumentMarker*>(markers[markers.size() - 1])->setRenderedRect(range->boundingBox());
+            toRenderedDocumentMarker(markers[markers.size() - 1])->setRenderedRect(range->boundingBox());
         }
     }
 }