function addDirective(tDirectives, name, location, maxPriority, ignoreDirective, startAttrName,
                          endAttrName) {
      if (name === ignoreDirective) return null;
      var match = null;
      if (hasDirectives.hasOwnProperty(name)) {
        for (var directive, directives = $injector.get(name + Suffix),
            i = 0, ii = directives.length; i < ii; i++) {
          directive = directives[i];
          if ((isUndefined(maxPriority) || maxPriority > directive.priority) &&
               directive.restrict.indexOf(location) !== -1) {
            if (startAttrName) {
              directive = inherit(directive, {$$start: startAttrName, $$end: endAttrName});
            }
            if (!directive.$$bindings) {
              var bindings = directive.$$bindings =
                  parseDirectiveBindings(directive, directive.name);
              if (isObject(bindings.isolateScope)) {
                directive.$$isolateBindings = bindings.isolateScope;
              }
            }
            tDirectives.push(directive);
            match = directive;
          }
        }
      }
      return match;
    }
looks up the directive and decorates it with exception handling and proper parameters. We
call this the boundDirective.

@param {string} name name of the directive to look up.
@param {string} location The directive must be found in specific format.
  String containing any of theses characters:

  * `E`: element name
  * `A': attribute
  * `C`: class
  * `M`: comment
@returns {boolean} true if directive was added.