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/TableViewer.java
*  (non-Javadoc)
	 * @see org.eclipse.jface.viewers.StructuredViewer#doUpdateItem(org.eclipse.swt.widgets.Widget, java.lang.Object, boolean)
	 */
	protected void doUpdateItem(Widget widget, Object element, boolean fullMap) {
		if (widget instanceof TableItem) {
			final TableItem item = (TableItem) widget;
			
			if (fullMap) {
				associate(element, item);
			} else {
				item.setData(element);
				mapElement(element, item);
			}
			IBaseLabelProvider prov = getLabelProvider();
			ITableLabelProvider tprov = null;			
			if (prov instanceof ITableLabelProvider) {
				tprov = (ITableLabelProvider) prov;
			} 
			
			
			int columnCount = table.getColumnCount();
			TableItem ti = item;
			colorAndFontCollector.setFontsAndColors(element);
			
			
			
			for (int column = 0; column < columnCount || column == 0; column++) {
				
				String text = "";
				Image image = null;