Bug 174701 [Viewers] ViewerRow should be reused instead of connected to the Item
Currently we create a ViewerRow ver every Item we create this can degrade performance, we should cache the row and reuse it
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/AbstractTreeViewer.java
*            levels of the tree
	 */
	public void setAutoExpandLevel(int level) {
		expandToLevel = level;
	}
	/**
	 * The <code>AbstractTreeViewer</code> implementation of this method
	 * checks to ensure that the content provider is an
	 * <code>ITreeContentProvider</code>.
	 */
	public void setContentProvider(IContentProvider provider) {
		
		super.setContentProvider(provider);
	}
	protected void assertContentProviderType(IContentProvider provider) {
		Assert.isTrue(provider instanceof ITreeContentProvider
				|| provider instanceof ITreePathContentProvider);
	}
	/**
	 * Sets the expand state of the given item.
	 * 
	 * @param item
	 *            the item
	 * @param expand
	 *            the expand state of the item
	 */
	protected abstract void setExpanded(Item item, boolean expand);
	/**
	 * Sets which nodes are expanded in this viewer's tree. The given list
	 * contains the elements that are to be expanded; all other nodes are to be