Review

class TypeInference {
  private void redeclare(FlowScope scope, String varName, JSType varType) {
    if (varType == null) {
      varType = getNativeType(JSTypeNative.UNKNOWN_TYPE);
    }
    if (unflowableVarNames.contains(varName)) {
      return;
    }
    scope.inferSlotType(varName, varType);
  }

}