function makeField(id, classnameRequiredToSplitBlockquote) {
  const field = new Field(id);
  field.registerPlugin(new EnterHandler());
  field.registerPlugin(new Blockquote(classnameRequiredToSplitBlockquote));

  events.listen(field, Field.EventType.BEFORECHANGE, () => {
    // set the global flag that beforechange was fired.
    firedBeforeChange = true;
  });
  events.listen(field, Field.EventType.DELAYEDCHANGE, () => {
    // set the global flag that delayed change was fired.
    firedDelayedChange = true;
  });

  return field;
}
Creates a field with only the enter handler plugged in, for testing.
@param {string} id A DOM id.
@return {!Field} A field.