Bug 322356 EPS's isPartVisible(MPart) method does not consider placeholders
SSIA
tests/org.eclipse.e4.ui.tests/src/org/eclipse/e4/ui/tests/application/HeadlessContextPresentationEngine.java
.getName() + " eclipse context"; 
			final IEclipseContext createdContext = (parentContext != null) ? parentContext
					.createChild(contextName) : EclipseContextFactory
					.create(contextName);
			populateModelInterfaces(mcontext, createdContext, element
					.getClass().getInterfaces());
			for (String variable : mcontext.getVariables()) {
				createdContext.declareModifiable(variable);
			}
			mcontext.setContext(createdContext);
			if (element instanceof MContribution && createContributions) {
				MContribution contribution = (MContribution) element;
				String uri = contribution.getContributionURI();
				if (uri != null) {
					Object clientObject = contributionFactory.create(uri,
							createdContext);
					contribution.setObject(clientObject);
				}
			}
			if (parentContext != null
					&& parentContext.getLocal(IContextConstants.ACTIVE_CHILD) == null) {
				parentContext.set(IContextConstants.ACTIVE_CHILD,
						createdContext);
			}
		}
		if (element instanceof MPartStack) {
			MPartStack container = (MPartStack) element;
			MPart active = (MPart) container.getSelectedElement();
			if (active != null) {
				createGui(active, container, getParentContext(active));