Ensure FullScreen button has classname set on render.

When the FullScreen icon is first rendered, the button within it is not having the inactive classname set. The class name is set on toggling fullscreen on/off - just not being set on render.

src/ol/control/FullScreen.js

@@ -165,6 +165,7 @@ class FullScreen extends Control {
 
     const tipLabel = options.tipLabel ? options.tipLabel : 'Toggle full-screen';
     this.button_.setAttribute('type', 'button');
+    this.setClassName_(this.button_, this.isInFullscreen_);
     this.button_.title = tipLabel;
     this.button_.appendChild(this.labelNode_);