Description:
------------
When a message formatter formats selects with nested variables, its behaviour is 
buggy.

Test script:
---------------
// attempting to translate file size
$locale = 'en_US';
$args = array(1.23435, 'M');
$format = "{1, select, k {{0} kB} M {{0} MB} other {{0} B}}";
echo "#1: ". msgfmt_format_message($locale, $format, $args) ."\n";

$format = "{1, select, k {{0} kB} M {{0, number, #.##} MB} other {{0} B}}";
echo "#2: ". msgfmt_format_message($locale, $format, $args) ."\n";
echo "Error? ". intl_get_error_message() ."\n";

Expected result:
----------------
#1: 1.23435 MB
#2: 1.23 MB
Error? U_ZERO_ERROR


Actual result:
--------------
#1: 1.23435 MB
#2: 
Error? Creating message formatter failed: U_ARGUMENT_TYPE_MISMATCH