src/vs/editor/common/viewLayout/linesLayout.ts/LinesLayout/getWhitespaceMinWidth
class LinesLayout:	public getWhitespaceMinWidth(): number {
		this._checkPendingChanges();
		if (this._minWidth === -1) {
			let minWidth = 0;
			for (let i = 0, len = this._arr.length; i < len; i++) {
				minWidth = Math.max(minWidth, this._arr[i].minWidth);
			}
			this._minWidth = minWidth;
		}
		return this._minWidth;
	}