Platform: avoid potential race conditions on load.

src/Magnum/Platform/Test/EmscriptenApplicationTest.html

@@ -14,7 +14,6 @@
       <div class="mn-status" id="status">Initialization...</div>
       <div class="mn-status-description" id="status-description"></div>
       <script src="EmscriptenApplication.js"></script>
-      <script async="async" src="PlatformEmscriptenApplicationTest.js"></script>
       <script>
       /* To test keyboard capture directly on the canvas */
       Module.keyboardListeningElement = Module.canvas;
@@ -22,6 +21,7 @@
           event.target.focus();
       });
       </script>
+      <script async="async" src="PlatformEmscriptenApplicationTest.js"></script>
     </div></div></div>
   </div>
 </body>