Bug 337002 EPartService leaks previously active part
A reference is kept to the previously active part. This is unnecessary. We only need it to fire events. After the deactivation events have been fired, we should no longer need to keep it lying around.
tests/org.eclipse.e4.ui.tests/src/org/eclipse/e4/ui/tests/application/EPartServiceTest.java
MPart partBackA = (MPart) partStackA.getChildren().get(1);
		partStackA.setSelectedElement(partFrontA);
		MWindow windowB = application.getChildren().get(1);
		MPartStack partStackB = (MPartStack) windowB.getChildren().get(0);
		MPart partFrontB = (MPart) partStackB.getChildren().get(0);
		MPart partBackB = (MPart) partStackB.getChildren().get(1);
		partStackB.setSelectedElement(partFrontB);
		getEngine().createGui(windowA);
		getEngine().createGui(windowB);
		EPartService partServiceA = (EPartService) windowA.getContext().get(
				EPartService.class.getName());
		EPartService partServiceB = (EPartService) windowB.getContext().get(
				EPartService.class.getName());
		partServiceA.bringToTop(partBackB);
		assertEquals(partStackA.getSelectedElement(), partFrontA);
		assertEquals(partStackB.getSelectedElement(), partFrontB);
		partServiceB.bringToTop(partBackA);
		assertEquals(partStackA.getSelectedElement(), partFrontA);
		assertEquals(partStackB.getSelectedElement(), partFrontB);
		partServiceA.bringToTop(partBackA);
		assertEquals(partStackA.getSelectedElement(), partBackA);
		assertEquals(partStackB.getSelectedElement(), partFrontB);
		partServiceB.bringToTop(partBackB);
		assertEquals(partStackA.getSelectedElement(), partBackA);
		assertEquals(partStackB.getSelectedElement(), partBackB);
	}
	public void testBringToTop_PartInAnotherWindow_myService() {
		MApplication application = createApplication(new String[] {
				"partFrontA", "partBackA" }, new String[] { "partFrontB",
				"partBackB" });