Revert "Defer expensive project reference computation during selection changes"

This reverts commit 3aaea37e05f6d0e2ff90db5b2030dca8b1a98c83 and the
follow-up Javadoc fix in 3b23ac5.

The override of updateSelection() introduced in #3871 left
CloseUnrelatedProjectsAction enabled after the last unrelated project
was closed, because the cheap enablement check no longer consulted the
project graph. Restoring the previous behavior is the simplest fix
while a follow-up addresses the original UI-thread cost separately.

Refs #2636

Author: vogella

bundles/org.eclipse.ui.ide/extensions/org/eclipse/ui/actions/CloseUnrelatedProjectsAction.java

@@ -30,7 +30,6 @@
 import org.eclipse.jface.dialogs.IDialogConstants;
 import org.eclipse.jface.dialogs.MessageDialogWithToggle;
 import org.eclipse.jface.preference.IPreferenceStore;
-import org.eclipse.jface.viewers.IStructuredSelection;
 import org.eclipse.jface.window.IShellProvider;
 import org.eclipse.osgi.util.NLS;
 import org.eclipse.swt.widgets.Shell;
@@ -131,25 +130,6 @@ public CloseUnrelatedProjectsAction(IShellProvider provider){
 		initAction();
 	}
 
-	/**
-	 * Overrides to avoid calling the expensive
-	 * {@code computeRelated(List)} during selection changes. Uses only
-	 * the raw selection to determine enablement.
-	 */
-	@Override
-	protected boolean updateSelection(IStructuredSelection s) {
-		selectionDirty = true;
-		if (!selectionIsOfType(IResource.PROJECT)) {
-			return false;
-		}
-		for (IResource resource : super.getSelectedResources()) {
-			if (resource instanceof IProject project && project.isOpen()) {
-				return true;
-			}
-		}
-		return false;
-	}
-
 	@Override
 	public void run() {
 		if (promptForConfirmation()) {