title: Popup shows up and then it closes instantly
body: <p>I'm trying follow the guide from angularfire2 docs on github, but when I try to open the popup window for google login it just closes instantly.</p>
  
  <p>I've tried with different browsers, but I can't figure out what's going on.</p>
  
  <p>Here's the HTML of my form component:</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;div class="container " &gt;
  &lt;h2 class="date"&gt;Wallet manager&lt;/h2&gt;
  &lt;h1&gt;SUBBO&lt;/h1&gt;
  
  &lt;form&gt;
    &lt;div class="form-group"&gt;
      &lt;label class="date" for="exampleInputEmail1"&gt;Email address&lt;/label&gt;
      &lt;input type="email" class="form-control" id="exampleInputEmail1" aria-describedby="emailHelp" placeholder="Enter email"&gt;
      &lt;small id="emailHelp" class="form-text text-muted"&gt;We'll never share your email with anyone else.&lt;/small&gt;
    &lt;/div&gt;
    &lt;div class="form-group"&gt;
      &lt;label class="date" for="exampleInputPassword1"&gt;Password&lt;/label&gt;
      &lt;input type="password" class="form-control" id="exampleInputPassword1" placeholder="Password"&gt;
    &lt;/div&gt;
    &lt;button type="submit" (click)="login()" style="margin-top:20px" class="btn btn-outline-warning"&gt;Login&lt;/button&gt;
    &lt;button type="submit" (click)="logout()" style="margin-top:20px" class="btn btn-outline-warning"&gt;Logout&lt;/button&gt;
  &lt;/form&gt;
  
  &lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>and here is the code:</p>
  
  <pre><code>import { Component, OnInit } from '@angular/core';
  import { AngularFireAuth } from 'angularfire2/auth';
  import * as firebase from 'firebase/app';
  
  @Component({
    selector: 'app-login-form',
    templateUrl: './login-form.component.html',
    styleUrls: ['./login-form.component.css']
  })
  export class LoginFormComponent implements OnInit {
  
    constructor(public afAuth: AngularFireAuth) {
    }
    login() {
      this.afAuth.auth.signInWithPopup(new firebase.auth.GoogleProvider());
    }
    logout() {
      this.afAuth.auth.signOut();
    }
  
    ngOnInit() {
    }
  
  }
  </code></pre>
  
  <p>With the login button I call Login() and I was expecting the window to popup and stay there, but it close immediately.</p>
  
  <p>I've uploaded the project to Firebase and it give's me the same problem:
  <a href="https://subbo-wallet-manager.firebaseapp.com/" rel="noreferrer">https://subbo-wallet-manager.firebaseapp.com/</a></p>