src/vs/editor/common/model/textModelSearch.ts/LineFeedCounter/constructor
class LineFeedCounter:	constructor(text: string) {
		const lineFeedsOffsets: number[] = [];
		let lineFeedsOffsetsLen = 0;
		for (let i = 0, textLen = text.length; i < textLen; i++) {
			if (text.charCodeAt(i) === CharCode.LineFeed) {
				lineFeedsOffsets[lineFeedsOffsetsLen++] = i;
			}
		}
		this._lineFeedsOffsets = lineFeedsOffsets;
	}