Bug 126779 [IDE] Removed deprecated project capabilities API and implementation
It was created then deprecated before 2.0 shipped. As has never been API and we don't use it we should delete it.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/ide/registry/CapabilityRegistry.java
/* (non-Javadoc)
     * Method declared on IWorkbenchAdapter.
     */
    public Object[] getChildren(Object o) {
        return capabilities.toArray();
    }
    /**
     * Returns the membership set ids that the specified
     * capability belongs to.
     */
    public String[] getMembershipSetIds(Capability capability) {
        IProjectNatureDescriptor desc = capability.getNatureDescriptor();
        if (desc == null)
            return EMPTY_ID_LIST;
        return desc.getNatureSetIds();
    }
    /**
     * Returns the miscellaneous category, or <code>null</code>
     * if none.
     */
    public Category getMiscCategory() {
        return miscCategory;
    }
    /**
     * Returns the capability ids that are prerequisites
     * of the specified capability.
     */
    public String[] getPrerequisiteIds(Capability capability) {
        IProjectNatureDescriptor desc = capability.getNatureDescriptor();
        if (desc == null)