Bug 25827 Disposing of MemberFilterActionGroup
Build 2.0.2 and 2.1 When investigating an editor memory leak PR we found out that this group has a dispose method which is never called. When we then called from the editor it throw an exeption (viewer was disposed). Don't know if the group really needs dispose() if so it should get called.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/JavaOutlinePage.java
* Returns the primary type of a compilation unit (has the same
	 * name as the compilation unit).
	 * 
	 * @param compilationUnit the compilation unit
	 * @return returns the primary type of the compilation unit, or
	 * <code>null</code> if is does not have one
	 */
	protected IType getMainType(ICompilationUnit compilationUnit) {
		String name= compilationUnit.getElementName();
		int index= name.indexOf('.');
		if (index != -1)
			name= name.substring(0, index);
		IType type= compilationUnit.getType(name);
		return type.exists() ? type : null;
	}
	/**
	 * Returns the primary type of a class file.
	 * 
	 * @param classFile the class file
	 * @return returns the primary type of the class file, or <code>null</code>
	 * if is does not have one
	 */
	protected IType getMainType(IClassFile classFile) {
		try {
			IType type= classFile.getType();
			return type.exists() ? type : null;
		} catch (JavaModelException e) {
			return null;	
		}
	}