Merge "Check the count of the families in a default collection."

    _script_to_font_map = collections.defaultdict(set)

    _fallback_chain = []

    tree = ElementTree.parse(fonts_xml_path)

    for family in tree.findall('family'):

    families = tree.findall('family')

    # Minikin supports up to 254 but users can place their own font at the first

    # place. Thus, 253 is the maximum allowed number of font families in the

    # default collection.

    assert len(families) < 254, (

        'System font collection can contains up to 253 font families.')

    for family in families:

        name = family.get('name')

        variant = family.get('variant')

        langs = family.get('lang')