fix(signin): autofocus on sign in button when password is not required (#5657) r=@vladikoff

Fixes #5636.

(Circle CI fail due to old Git SHA)

app/scripts/templates/sign_in.mustache

@@ -52,7 +52,7 @@
 
         {{^chooserAskForPassword}}
           <div class="button-row">
-            <button type="submit" class="use-logged-in">{{{buttonSignInText}}}</button>
+            <button type="submit" class="use-logged-in" autofocus>{{{buttonSignInText}}}</button>
           </div>
 
           <div class="links">

app/tests/spec/views/sign_in.js

@@ -614,6 +614,7 @@ define(function (require, exports, module) {
             assert.ok(view.$('.avatar-view').length, 'should show suggested avatar');
             assert.notOk(view.$('.password').length, 'should not show password input');
             assert.isTrue(isEventLogged(metrics, 'signin.ask-password.skipped'));
+            assert.ok(view.$('.use-logged-in').attr('autofocus'), 'should autofocus when password is not required');
           });
       });