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
MPerspectiveStack perspectiveStack = AdvancedFactoryImpl.eINSTANCE
				.createPerspectiveStack();
		window.getChildren().add(perspectiveStack);
		window.setSelectedElement(perspectiveStack);
		MPerspective perspectiveA = AdvancedFactoryImpl.eINSTANCE
				.createPerspective();
		perspectiveStack.getChildren().add(perspectiveA);
		perspectiveStack.setSelectedElement(perspectiveA);
		MPart partA = BasicFactoryImpl.eINSTANCE.createPart();
		perspectiveA.getChildren().add(partA);
		perspectiveA.setSelectedElement(partA);
		MPerspective perspectiveB = AdvancedFactoryImpl.eINSTANCE
				.createPerspective();
		perspectiveStack.getChildren().add(perspectiveB);
		MPlaceholder placeholderB = AdvancedFactoryImpl.eINSTANCE
				.createPlaceholder();
		placeholderB.setRef(partB);
		partB.setCurSharedRef(placeholderB);
		perspectiveB.getChildren().add(placeholderB);
		perspectiveB.setSelectedElement(placeholderB);
		MPlaceholder placeholderC = AdvancedFactoryImpl.eINSTANCE
				.createPlaceholder();
		placeholderC.setRef(partC);
		partC.setCurSharedRef(placeholderC);
		perspectiveB.getChildren().add(placeholderC);
		initialize(applicationContext, application);
		getEngine().createGui(window);
		EPartService partService = window.getContext().get(EPartService.class);
		partService.activate(partA);
		assertEquals(partA, partService.getActivePart());