fs: make 'end' work with ReadStream without 'start'

Make `fs.createReadStream({ end: 42 })` work.

Before this commit, it worked only when used like this:
`fs.createReadStream({ start: 0, end: 42 })` - only when `start` was specified
by the caller.

Fixes #4423.

lib/fs.js

@@ -1403,7 +1403,7 @@ function ReadStream(path, options) {
   this.mode = options.hasOwnProperty('mode') ? options.mode : 438; /*=0666*/
 
   this.start = options.hasOwnProperty('start') ? options.start : undefined;
-  this.end = options.hasOwnProperty('start') ? options.end : undefined;
+  this.end = options.hasOwnProperty('end') ? options.end : undefined;
   this.autoClose = options.hasOwnProperty('autoClose') ?
       options.autoClose : true;
   this.pos = undefined;