makeForUpdate() {
    const context = this.loopContext;
    const choiceContext = this.choiceContext;
    const forkContext = this.forkContext;

    // Make the next paths of the test.
    if (context.testSegments) {
      finalizeTestSegmentsOfFor(context, choiceContext, forkContext.head);
    } else {
      context.endOfInitSegments = forkContext.head;
    }

    // Update state.
    const updateSegments = forkContext.makeDisconnected(-1, -1);

    context.continueDestSegments = context.updateSegments = updateSegments;
    forkContext.replaceHead(updateSegments);
  }
Makes a code path segment for the update part of a ForStatement.
@returns {void}