swarm at r28020

Every call site in the generated code for LinkedHashMap_LinkedHashMap looks like

    LinkedHashMap_LinkedHashMap(null, null, null, <varies>, <varies>);

The code is not specialized, which drags in _LinkedIdentityHashMap and _LinkedCustomHashMap$ which are otherwise unreferenced (this costs only ~2k, but still is unshaken)

LinkedHashMap_LinkedHashMap: function(equals, hashCode, isValidKey, $K, $V) {
  var t1;
  if (hashCode == null) {
    if (equals == null) {
      t1 = new P._LinkedHashMap(0, null, null, null, null, null, 0);
      H.setRuntimeTypeInfo(t1, [$K, $V]);
      return t1;
    }
    hashCode = P._defaultHashCode$closure;
  } else {
    if ((P.identityHashCode$closure == null ? hashCode == null : P.identityHashCode$closure === hashCode) && (P.identical$closure == null ? equals == null : P.identical$closure === equals)) {
      t1 = new P._LinkedIdentityHashMap(0, null, null, null, null, null, 0);
      H.setRuntimeTypeInfo(t1, [$K, $V]);
      return t1;
    }
    if (equals == null)
      equals = P._defaultEquals$closure;
  }
  return P._LinkedCustomHashMap$(equals, hashCode, isValidKey, $K, $V);
},

I could not repro this on a simpler example, and the similarly structured LinkedHashSet is optimized, so type inference on the larger program must be getting confused by something.