data->metrics->TextDimensionsCallback(aChar, aFont, aData);
return data->metrics->TextDimensionsCallback(aString, aLen, aFont, aData);
StaticTextDimensionsCallback(FcChar32 aChar, nsFontXft *aFont, void *aData){    TextDimensionsData *data = (TextDimensionsData *)aData;    data->metrics->TextDimensionsCallback(aChar, aFont, aData);}