src/vs/editor/common/diff/diffComputer.ts/CharSequence/getEndLineNumber
class CharSequence:	public getEndLineNumber(i: number): number {
		if (i === -1) {
			// the end line number of the element before the first element
			// is the start line number of the first element
			return this.getStartLineNumber(i + 1);
		}
		this._assertIndex(i, this._lineNumbers);

		if (this._charCodes[i] === CharCode.LineFeed) {
			return this._lineNumbers[i] + 1;
		}
		return this._lineNumbers[i];
	}