Bug 299340 [CommonNavigator] Enable new CNF tests
Enable the contributed CNF tests, make minor test improvements.
tests/org.eclipse.ui.tests.navigator/src/org/eclipse/ui/tests/navigator/LabelProviderTest.java
NavigatorContentExtension ext = (NavigatorContentExtension) _contentService
				.getContentExtensionById(cpToGet);
		TestLabelProvider tp = (TestLabelProvider) ext.getLabelProvider();
		if (blank)
			tp._blank = true;
		else
			tp._null = true;
	}
	
	
	
	public void blankLabelProviderOverride(int nce, boolean blank, String suffix)
			throws Exception {
		String overriddenCp = TEST_CONTENT_OVERRIDDEN1 + suffix; 
		String overrideCp = TEST_CONTENT_OVERRIDE1 + suffix; 
		String checkColor = "Green";
		switch (nce) {
		case NONE:
			break;
		case OVERRIDDEN:
			setBlank(overriddenCp, blank);
			break;
		case OVERRIDING:
			checkColor = "Red";
			setBlank(overrideCp, blank);
			break;
		case BOTH:
			setBlank(overriddenCp, blank);
			setBlank(overrideCp, blank);
			break;