Use a small JavaScript file to verify CDN liveness

Move the code that hides the message about CDN blocking from Ode
itself to a small little JavaScript file. So people on slow links will
not see the warning message for the time it takes to load all of Ode,
which might be a while.

Change-Id: I9c10ab43bb7c2c69e149b25714131a35735dfcd1

appinventor/appengine/build.xml

@@ -634,6 +634,8 @@
       <arg value="${build.extra.dir}"/>
       <arg line="${client.flags} ${client.module}"/>
     </java>
+    <copy todir="${build.war.dir}/ode"
+          file="${appinventor.dir}/appengine/extra/cdnok.js" />
   </target>
 
   <target name="devmode"

appinventor/appengine/extra/cdnok.js

@@ -0,0 +1,5 @@
+function cdnok() {
+  let odeblock = document.getElementById("odeblock");
+  odeblock.style.display = 'none';
+}
+cdnok();

appinventor/appengine/src/com/google/appinventor/client/Ode.java

@@ -74,9 +74,6 @@
 import com.google.gwt.core.client.Callback;
 import com.google.gwt.core.client.EntryPoint;
 import com.google.gwt.core.client.GWT;
-import com.google.gwt.dom.client.Document;
-import com.google.gwt.dom.client.Element;
-import com.google.gwt.dom.client.Style;
 import com.google.gwt.event.dom.client.ClickHandler;
 import com.google.gwt.event.dom.client.MouseWheelEvent;
 import com.google.gwt.event.dom.client.MouseWheelHandler;
@@ -648,13 +645,6 @@ public void onUncaughtException(Throwable e) {
       }
     });
 
-    // First order of business. Let's hide the div with the message about
-    // how access to Ode is blocked. If we get here, Ode is loaded, so there
-    // is no block! (yeah!)
-
-    Element element = Document.get().getElementById("odeblock");
-    element.getStyle().setDisplay(Style.Display.NONE);
-
     // Initialize global Ode instance
     instance = this;
 

appinventor/appengine/war/WEB-INF/appengine-web.xml

@@ -20,6 +20,7 @@
 
     <!-- These are not cached on purpose -->
     <include path="/ode/**.nocache.*" expiration="0s" />
+    <include path="/ode/cdnok.js" expiration="3600s" />
     <include path="/index.html" expiration="0s" />
 
     <include path="/ode/**.cache.*" expiration="365d" />

appinventor/appengine/war/index.jsp

@@ -73,6 +73,7 @@
         </h1>
     </div>
     <script type="text/javascript" src="static/closure-library/closure/goog/base.js"></script>
+    <script type="text/javascript" src="<%= odeBase %>ode/cdnok.js"></script>
     <script type="text/javascript" src="<%= odeBase %>ode/ode.nocache.js"></script>
     <script src="static/leaflet/leaflet.js"></script>
     <script src="static/leaflet/leaflet.toolbar.js"></script>