src/vs/editor/common/viewLayout/linesLayout.ts/LinesLayout/_findWhitespaceIndex
class LinesLayout:	private _findWhitespaceIndex(id: string): number {
		const arr = this._arr;
		for (let i = 0, len = arr.length; i < len; i++) {
			if (arr[i].id === id) {
				return i;
			}
		}
		return -1;
	}