src/vs/workbench/api/common/extHostTypes.ts/Range/union
class Range:	union(other: Range): Range {
		if (this.contains(other)) {
			return this;
		} else if (other.contains(this)) {
			return other;
		}
		const start = Position.Min(other.start, this._start);
		const end = Position.Max(other.end, this.end);
		return new Range(start, end);
	}