src/vs/editor/common/textModelEvents.ts/InternalModelContentChangeEvent/_mergeChangeEvents
class InternalModelContentChangeEvent:	private static _mergeChangeEvents(a: IModelContentChangedEvent, b: IModelContentChangedEvent): IModelContentChangedEvent {
		const changes = ([] as IModelContentChange[]).concat(a.changes).concat(b.changes);
		const eol = b.eol;
		const versionId = b.versionId;
		const isUndoing = (a.isUndoing || b.isUndoing);
		const isRedoing = (a.isRedoing || b.isRedoing);
		const isFlush = (a.isFlush || b.isFlush);
		return {
			changes: changes,
			eol: eol,
			versionId: versionId,
			isUndoing: isUndoing,
			isRedoing: isRedoing,
			isFlush: isFlush
		};
	}