Merge pull request #6078 from rschmukler/master

add objectMode to node stream.WritableOptions

node/node.d.ts

@@ -1687,6 +1687,7 @@ declare module "stream" {
     export interface WritableOptions {
         highWaterMark?: number;
         decodeStrings?: boolean;
+        objectMode?: boolean;
     }
 
     export class Writable extends events.EventEmitter implements NodeJS.WritableStream {