Fix failing StackRendererTest Test

Calling notifyListeners is not necessary any more.

Fixes: eclipse-platform/eclipse.platform.swt#1515

Author: BeckerWdf

tests/org.eclipse.e4.ui.tests/src/org/eclipse/e4/ui/workbench/renderers/swt/StackRendererTest.java

@@ -49,14 +49,12 @@
 import org.eclipse.e4.ui.tests.rules.WorkbenchContextRule;
 import org.eclipse.e4.ui.workbench.UIEvents;
 import org.eclipse.e4.ui.workbench.modeling.EModelService;
-import org.eclipse.swt.SWT;
 import org.eclipse.swt.custom.CTabFolder;
 import org.eclipse.swt.custom.CTabItem;
 import org.eclipse.swt.graphics.Image;
 import org.eclipse.swt.graphics.Rectangle;
 import org.eclipse.swt.widgets.Composite;
 import org.eclipse.swt.widgets.Control;
-import org.eclipse.swt.widgets.Event;
 import org.eclipse.swt.widgets.Label;
 import org.eclipse.swt.widgets.Widget;
 import org.junit.Before;
@@ -540,8 +538,6 @@ public void testOnboardingIsHiddenWhenEditorOpened() {
 		partStack.getChildren().add(part1);
 		partStack.setSelectedElement(part1);
 
-		tabFolder.notifyListeners(SWT.Paint, new Event());
-
 		expected = new Rectangle(StackRenderer.ONBOARDING_SPACING, StackRenderer.ONBOARDING_TOP_SPACING, 0, 0);
 		assertEquals(expected, outerOnboardingComposite.getBounds());
 	}