(Fix #215) better error printing in editor & extension, adds mapping for editor

extension/content_script.js

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Glue code that runs on the page referencing dart web components.
 // Some logic has to be placed here rather than on the background page
 // because of chrome security restrictions.
 
 // Port used to send requests to the background page to proxy urls.
 var proxyPort = null;
@@ skipping 43 matching lines @@
             // Replace the contents of the existing document with the
             // proxied content at the url with an additional .html added.
             // We prefer this versus redirecting to the page with an extra
             // .html so that refreshing this page does the right thing.
             var newDoc = document.open("text/html", "replace");
             newDoc.write(content);
             newDoc.close();
           }
         }
       }, 100);
+    } else if (msg.type == 'MESSAGES') {
+      var messages = msg.messages;
+      for (var i = 0; i < messages.length; i++) {
+        var level = messages[i][0];
+        var message = messages[i][1];
+        if (level == 'SEVERE') {
+          window.console.error(message);
+        } else if (level == 'WARNING') {
+          window.console.warn(message);
+        } else {
+          window.console.info(message);
+        }
+      }
     }
   })
 
 }
 
 document.addEventListener("DOMContentLoaded", function() {
   // Don't re-run the compiler on code we just generated.
   if (document.childNodes.length > 1 &&
       document.childNodes[1] instanceof Comment &&
       document.childNodes[1].nodeValue.indexOf(
@@ skipping 10 matching lines @@
 });
 
 window.addEventListener("message", function(event) {
   if (event.source != window)
     return;
 
   if (event.data.type == "PARSE") {
     onRequestParse();
   }
 }, false);