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
MWindow window = application.getChildren().get(0);
		MPartDescriptor partDescriptor = org.eclipse.e4.ui.model.application.descriptor.basic.impl.BasicFactoryImpl.eINSTANCE
				.createPartDescriptor();
		partDescriptor.setElementId("partId");
		application.getDescriptors().add(partDescriptor);
		getEngine().createGui(window);
		EPartService partService = (EPartService) window.getContext().get(
				EPartService.class.getName());
		MPart part = partService.showPart("partId", partState);
		assertNotNull(part);
		assertEquals("partId", part.getElementId());
		assertEquals(part, partService.getActivePart());
		MPart part2 = partService.showPart("partId", partState);
		assertEquals("Should not have instantiated a new MPart", part, part2);
		assertEquals(part, partService.getActivePart());
	}
	public void testShowPart_Id_PartAlreadyShown_ACTIVATE() {
		testShowPart_Id_PartAlreadyShown(PartState.ACTIVATE);
	}
	public void testShowPart_Id_PartAlreadyShown_CREATE() {
		testShowPart_Id_PartAlreadyShown(PartState.CREATE);
	}
	public void testShowPart_Id_PartAlreadyShown_VISIBLE() {
		testShowPart_Id_PartAlreadyShown(PartState.VISIBLE);
	}
	private void testShowPart_Id_IncorrectDescriptor(PartState partState) {
		MApplication application = createApplication(1, new String[1][0]);
		MWindow window = application.getChildren().get(0);
		MPartDescriptor partDescriptor = org.eclipse.e4.ui.model.application.descriptor.basic.impl.BasicFactoryImpl.eINSTANCE
				.createPartDescriptor();