Update fontchain_linter.py to be compatible with Compat font

def get_emoji_map(font):

    # Add normal characters

    emoji_map = copy.copy(get_best_cmap(font))

    reverse_cmap = {glyph: code for code, glyph in emoji_map.items()}

    reverse_cmap = {glyph: code for code, glyph in emoji_map.items() if not contains_pua(code) }

    # Add variation sequences

    vs_dict = get_variation_sequences_cmap(font).uvsDict

    return emoji_fonts[0]

def is_pua(x):

    return 0xE000 <= x <= 0xF8FF or 0xF0000 <= x <= 0xFFFFD or 0x100000 <= x <= 0x10FFFD

def contains_pua(sequence):

  if type(sequence) is tuple:

    return any([is_pua(x) for x in sequence])

  else:

    return is_pua(sequence)

def check_emoji_compat():

    ttf = open_font(get_emoji_font())

    meta = ttf['meta']

    assert meta, 'Compat font must have meta table'

    assert 'Emji' in meta.data, 'meta table should have \'Emji\' data.'

def check_emoji_font_coverage(emoji_font, all_emoji, equivalent_emoji):

    coverage = get_emoji_map(emoji_font)

        if sequence in {0x0000, 0x000D, 0x0020}:

            # The font needs to support a few extra characters, which is OK

            continue

        if contains_pua(sequence):

            # The font needs to have some PUA for EmojiCompat library.

            continue

        if sequence not in all_emoji:

          errors.append('%s support unexpected in the emoji font.' % printable(sequence))

                printable(second)))

    for glyph in set(coverage.values()):

        maps_to_glyph = [seq for seq in coverage if coverage[seq] == glyph]

        maps_to_glyph = [

            seq for seq in coverage if coverage[seq] == glyph and not contains_pua(seq) ]

        if len(maps_to_glyph) > 1:

            # There are more than one sequences mapping to the same glyph. We

            # need to make sure they were expected to be equivalent.

        ucd_path = sys.argv[3]

        parse_ucd(ucd_path)

        all_emoji, default_emoji, equivalent_emoji = compute_expected_emoji()

        check_emoji_compat()

        check_emoji_coverage(all_emoji, equivalent_emoji)

        check_emoji_defaults(default_emoji)