Bug 55256 [Colors/Fonts] Rollback change to ColorRegistry for gets() on colors that do not exist
bundles/org.eclipse.jface/src/org/eclipse/jface/resource/ColorRegistry.java
* value type: <code>org.eclipse.swt.graphics.Color</code>.
	 */
	private Map stringToColor = new HashMap(7);
	/**
	 * Table of known color data, keyed by symbolic color name (key type:
	 * <code>String</code>, value type: <code>org.eclipse.swt.graphics.RGB</code>).
	 */
	private Map stringToRGB = new HashMap(7);
	
	/**
	 * Runnable that cleans up the manager on disposal of the display.
	 */
	protected Runnable displayRunnable = new Runnable() {
		public void run() {
			clearCaches();
		}
	};
	/**
	 * Create a new instance of the receiver that is hooked to the current 
	 * display.
	 * 
	 * @see org.eclipse.swt.widgets.Display#getCurrent()
	 */
	public ColorRegistry() {
		this(Display.getCurrent());
	}
	/**
	 * Create a new instance of the receiver.
	 * 
	 * @param display the <code>Display</code> to hook into.