tty: make setRawMode() return this (and updated corresponding docs)

Author: ORESoftware

doc/api/tty.md

@@ -63,7 +63,7 @@ added: v0.7.7
 * `mode` {boolean} If `true`, configures the `tty.ReadStream` to operate as a
   raw device. If `false`, configures the `tty.ReadStream` to operate in its
   default mode. The `readStream.isRaw` property will be set to the resulting
-  mode.
+  mode. Returns `this` - the read stream instance.
 
 Allows configuration of `tty.ReadStream` so that it operates as a raw device.
 

lib/tty.js

@@ -71,9 +71,10 @@ ReadStream.prototype.setRawMode = function(flag) {
   const err = this._handle.setRawMode(flag);
   if (err) {
     this.emit('error', errors.errnoException(err, 'setRawMode'));
-    return;
+    return this;
   }
   this.isRaw = flag;
+  return this;
 };
 
 function WriteStream(fd) {