function onClick_(minusField) {
  // TODO: This is a dupe of the mutator code, anyway to unify?
  const block = minusField.getSourceBlock();

  if (block.isInFlyout) {
    return;
  }

  Blockly.Events.setGroup(true);
  const oldExtraState = getExtraBlockState(block);
  block.minus(minusField.args_);
  const newExtraState = getExtraBlockState(block);

  if (oldExtraState != newExtraState) {
    Blockly.Events.fire(
      new Blockly.Events.BlockChange(
        block,
        'mutation',
        null,
        oldExtraState,
        newExtraState,
      ),
    );
  }
  Blockly.Events.setGroup(false);
}
Calls block.minus(args) when the minus field is clicked.
@param {Blockly.FieldImage} minusField The field being clicked.
@private