src/vs/workbench/contrib/mergeEditor/browser/model/mapping.ts/LineRangeMapping/join
class LineRangeMapping:	public join(other: LineRangeMapping): LineRangeMapping {
		return new LineRangeMapping(
			this.inputRange.join(other.inputRange),
			this.outputRange.join(other.outputRange)
		);
	}