title: Rx.Observable.just is not a function in JSBIN & RxJS 5
body: <p>In JsBin, I got error "Rx.Observable.just is not a function" in Firefox &amp; Chrome. JsBin example : <a href="http://jsbin.com/vunuta/edit?html,js,console" rel="noreferrer">http://jsbin.com/vunuta/edit?html,js,console</a></p>
  
  <p>HTML :</p>
  
  <pre><code>script src="https://npmcdn.com/@reactivex/rxjs@5.0.0-beta.7/dist/global/Rx.umd.js"&gt;
  </code></pre>
  
  <p>Typescript :</p>
  
  <pre><code>Rx.Observable.from ([1,2,3]).subscribe(x =&gt; console.log(x)); // Work
  Rx.Observable.just (99).subscribe(x =&gt; console.log(x)); // Fail
  Rx.Observable.return (99).subscribe(x =&gt; console.log(x)); // Fail
  </code></pre>
  
  <p>Tx</p>