Bug 316298 [Compatibility] Support o.e.ui.menus visibleWhen
We need support in MCoreExpression for entire expressions created by the WorkbenchMenuService. They don't often use ReferenceExpressions to core expression definitions. PW
bundles/org.eclipse.e4.ui.model.workbench/src/org/eclipse/e4/ui/model/application/ui/impl/UiPackageImpl.java
* Returns the factory that creates the instances of the model.
	 * <!-- begin-user-doc -->
	 * <!-- end-user-doc -->
	 * @return the factory that creates the instances of the model.
	 * @generated
	 */
	public MUiFactory getUiFactory() {
		return (MUiFactory)getEFactoryInstance();
	}
	/**
	 * <!-- begin-user-doc -->
	 * <!-- end-user-doc -->
	 * @generated
	 */
	private boolean isCreated = false;
	/**
	 * Creates the meta-model objects for the package.  This method is
	 * guarded to have no affect on any invocation but its first.
	 * <!-- begin-user-doc -->
	 * <!-- end-user-doc -->
	 * @generated
	 */
	public void createPackageContents() {
		if (isCreated) return;
		isCreated = true;
		
		contextEClass = createEClass(CONTEXT);
		createEAttribute(contextEClass, CONTEXT__CONTEXT);
		createEAttribute(contextEClass, CONTEXT__VARIABLES);
		createEReference(contextEClass, CONTEXT__PROPERTIES);