Bug 89971 [Viewers] Viewers that use IViewerLabelProvider do too many instanceof checks
M6 Checking our viewer the calls to buildLabel are doing too many instanceof checks. As a result certain viewers (such as the table viewer) are twice as slow as they were in 3.0 due to these checks. I have written some performance suites to test the Table, Tree, List and Combo viewers. Table and Tree have this issue.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/StructuredViewer.java
* </p>
	 * 
	 * @param l
	 *            list of selected elements (element type: <code>Object</code>)
	 *            or <code>null</code> if the selection is to be cleared
	 * @param reveal
	 *            <code>true</code> if the selection is to be made visible,
	 *            and <code>false</code> otherwise
	 */
	protected abstract void setSelectionToWidget(List l, boolean reveal);
	/**
	 * Converts the selection to a <code>List</code> and calls
	 * <code>setSelectionToWidget(List, boolean)</code>. The selection is
	 * expected to be an <code>IStructuredSelection</code> of elements. If
	 * not, the selection is cleared.
	 * <p>
	 * Subclasses do not typically override this method, but implement
	 * <code>setSelectionToWidget(List, boolean)</code> instead.
	 * 
	 * @param selection
	 *            an IStructuredSelection of elements
	 * @param reveal
	 *            <code>true</code> to reveal the first element in the
	 *            selection, or <code>false</code> otherwise
	 */
	protected void setSelectionToWidget(ISelection selection, boolean reveal) {
		if (selection instanceof IStructuredSelection)
			setSelectionToWidget(((IStructuredSelection) selection).toList(), reveal);
		else
			setSelectionToWidget((List) null, reveal);