Platform: show Emscripten windowless app log only after it loads.

Otherwise it obscures the information about downloading.

src/Magnum/Platform/WindowlessEmscriptenApplication.js

@@ -37,6 +37,7 @@ var Module = {
         } else {
             Module.setStatus('');
             Module.setStatusDescription('');
+            document.getElementById('log').style.display = 'block';
         }
     }
 };
@@ -57,6 +58,8 @@ for(var i = 0; i != args.length; ++i) {
 
 Module.setStatus('Downloading...');
 
+document.getElementById('log').style.display = 'none';
+
 if(Module.canvas) Module.canvas.addEventListener('contextmenu', function(event) {
     event.preventDefault();
 }, true);