code: function strongDirFromContent (text) {
    var m = text.match(strongDirRegExp)
    if (!m) {
      return null
    }
    if (m[2] === undefined) {
      return 'ltr'
    }
    return 'rtl'
  }
docs: Gets directionality of the first strongly directional codepoint
  
  This is the rule the BIDI algorithm uses to determine the directionality of
  paragraphs ( http://unicode.org/reports/tr9/#The_Paragraph_Level ) and
  FSI isolates ( http://unicode.org/reports/tr9/#Explicit_Directional_Isolates ).
  
  TODO: Does not handle BIDI control characters inside the text.
  TODO: Does not handle unallocated characters.
  
  @param {string} text The text from which to extract initial directionality.
  @return {string} Directionality (either 'ltr' or 'rtl')