Bug 53881 [Colors] Color/Gradient registry should return default values.
There should be default values for when a user does .get() on a bad key.
bundles/org.eclipse.jface/src/org/eclipse/jface/resource/ColorRegistry.java
*/
	private Color createColor(String symbolicName, RGB rgb) {
		return new Color(display, rgb);
	}
	/**
	 * Dispose of all of the <code>Color</code>s in this iterator.
	 * 
	 * @param Iterator over <code>Collection</code> of <code>Color</code>
	 */
	private void disposeColors(Iterator iterator) {
		while (iterator.hasNext()) {
			Object next = iterator.next();
			((Color) next).dispose();
		}
	}
	/**
	 * Returns the <code>color</code> associated with the given symbolic color 
	 * name, or <code>null</code> if no such definition exists.
	 * 
	 * @param symbolicName symbolic color name.
	 * @return the <code>Color</code>.
	 */
	public Color get(String symbolicName) {
		Assert.isNotNull(symbolicName);
		Object result = stringToColor.get(symbolicName);
		if (result != null)
			return (Color) result;
		result = stringToRGB.get(symbolicName);
		if (result == null)
			return null;