Register the navigatable so that the toolbar actions work

Navigation actions from the toolbar to go to the next/previous
differences were not working without this.

Change-Id: I3747597c32044868bcbebf524306a1e06f7dd494
diff --git a/plugins/org.eclipse.emf.compare.ide.ui/src/org/eclipse/emf/compare/ide/ui/internal/structuremergeviewer/EMFCompareStructureMergeViewer.java b/plugins/org.eclipse.emf.compare.ide.ui/src/org/eclipse/emf/compare/ide/ui/internal/structuremergeviewer/EMFCompareStructureMergeViewer.java
index 843d548..5aa8d87 100644
--- a/plugins/org.eclipse.emf.compare.ide.ui/src/org/eclipse/emf/compare/ide/ui/internal/structuremergeviewer/EMFCompareStructureMergeViewer.java
+++ b/plugins/org.eclipse.emf.compare.ide.ui/src/org/eclipse/emf/compare/ide/ui/internal/structuremergeviewer/EMFCompareStructureMergeViewer.java
@@ -419,6 +419,7 @@
 				getCompareConfiguration().getAdapterFactory(), getViewer()));
 
 		navigatable = new Navigatable(getViewer(), getContentProvider());
+		getControl().setData(INavigatable.NAVIGATOR_PROPERTY, navigatable);
 
 		toolBar = createToolBar(CompareViewerPane.getToolBarManager(parent));
 		getViewer().addSelectionChangedListener(getToolBar());