Remove obsolete PropertyEditorManager cleanup task

[ptziegler]

The registry field no longer exists since openjdk/jdk@d46ed5c. Neither the IDE nor WindowBuilder support such ancient Java versions and this is therefore dead code.

windowbuilder/org.eclipse.wb.core.java/src/org/eclipse/wb/internal/core/utils/state/EditorState.java

Lines 254 to 276 in a91864d

	/**
	* Clear {@link PropertyEditorManager} cache to prevent {@link Class} and {@link ClassLoader}
	* leaks.
	*/
	private void dispose_PropertyEditorManager() {
	ExecutionUtils.runIgnore(new RunnableEx() {
	@Override
	@SuppressWarnings("rawtypes")
	public void run() throws Exception {
	Map registry =
	(Map) ReflectionUtils.getFieldObject(PropertyEditorManager.class, "registry");
	if (registry != null) {
	for (Iterator I = registry.entrySet().iterator(); I.hasNext();) {
	Map.Entry entry = (Map.Entry) I.next();
	Class editorClass = (Class) entry.getValue();
	if (isLoadedFrom(editorClass)) {
	I.remove();
	}
	}
	}
	}
	});
	}