makeWhileTest(test) {
    const context = this.loopContext;
    const forkContext = this.forkContext;
    const testSegments = forkContext.makeNext(0, -1);

    // Update state.
    context.test = test;
    context.continueDestSegments = testSegments;
    forkContext.replaceHead(testSegments);
  }
Makes a code path segment for the test part of a WhileStatement.
@param {boolean|undefined} test The test value (only when constant).
@returns {void}