constructor(upperContext, type, label, breakContext) {
		/**
		 * The previous `LoopContext`.
		 * @type {LoopContext}
		 */
		this.upper = upperContext;

		/**
		 * The AST node's `type` for the loop.
		 * @type {string}
		 */
		this.type = type;

		/**
		 * The label for the loop from an enclosing `LabeledStatement`.
		 * @type {string|null}
		 */
		this.label = label;

		/**
		 * The fork context for when `break` is encountered.
		 * @type {ForkContext}
		 */
		this.brokenForkContext = breakContext.brokenForkContext;
	}
Creates a new instance.
@param {LoopContext|null} upperContext The previous `LoopContext`.
@param {string} type The AST node's `type` for the loop.
@param {string|null} label The label for the loop from an enclosing `LabeledStatement`.
@param {BreakContext} breakContext The context for breaking the loop.