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

extension/background.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 interacts with dwc_compiler.dart to proxy arbitrary content
 // for urls.
 
 
 var existingRuleIds = {};
 var onParse = null;
 
 // TODO(jacobr): determine whether it is a bug or feature that we need to call
 // this.  Without the next line, stale declarativeWebRequest rules from the
 // previous time the extension was run conflict with rules from the current
 // running version causing the extension to sometimes crash due to conflicting
 // redirect requests.
 chrome.declarativeWebRequest.onRequest.removeRules();
 
 // TODO(jacobr): set the onParse property directly from Dart.
 function setOnParseCallback(cb) {
   onParse = cb;
 }
 
 function proxyUrls(port, requests) {
   // Unfortunately we have to create the data urls from the content script due
   // to chrome security restrictions.
   port.postMessage({type: 'CREATE_DATA_URLS', requests: requests});
 }
 
+function proxyMessages(port, messages) {
+  port.postMessage({type: 'MESSAGES', messages: messages});
+}
+
 function onProxyUrls(requests) {
   var rulesToAdd = [];
   var ruleIdsToRemove = [];
   for (var i = 0; i < requests.length; i++) {
     var request = requests[i];
     var url = request.url;
     var redirectUrl = request.redirectUrl;
     var rule = {
       conditions: [
         new chrome.declarativeWebRequest.RequestMatcher(
@@ skipping 26 matching lines @@
     port.onMessage.addListener(function(msg) {
       onParse(port, msg.url);
     });
   } else if (port.name == "proxy") {
     // Listen for requests to proxy urls.
     port.onMessage.addListener(function(msg) {
       onProxyUrls(msg.requests);
     });
   }
 });