dist/scripts/vendor.min.js
function constantWatchDelegate(scope, listener, objectEquality, constantInterp) {
      var unwatch = scope.$watch(function constantInterpolateWatch(scope) {
        unwatch();
        return constantInterp(scope);
      }, listener, objectEquality);
      return unwatch;
    }
function constantWatchDelegate(scope, listener, objectEquality, constantInterp) {
      var unwatch = scope.$watch(function constantInterpolateWatch(scope) {
        unwatch();
        return constantInterp(scope);
      }, listener, objectEquality);
      return unwatch;
    }
TODO: this is the same as the constantWatchDelegate in parse.js