lib/compiler-html2.js
function pushUnique( arr, item ) {
  if ( arr.indexOf( item ) > -1 ) return false;
  arr.push( item );
  return true;
}
function pushUnique( arr, item ) {
  if ( arr.indexOf( item ) > -1 ) return false;
  arr.push( item );
  return true;
}
function pushUnique ( arr , item ) { if ( arr . indexOf ( item ) > - 1 ) return false ; arr . push ( item ) ; return true ; }
Push `item` into `arr` if it is not already in.
Push item into arr if it is not already in .