Support source maps in server mode

tool/input_sdk/lib/html/ddc/html_ddc.dart

 /**
  * HTML elements and other resources for web-based applications that need to
  * interact with the browser and the DOM (Document Object Model).
  *
  * This library includes DOM element types, CSS styling, local storage,
  * media, speech, events, and more.
  * To get started,
  * check out the [Element] class, the base class for many of the HTML
  * DOM types.
  *
@@ skipping 19416 matching lines @@
      return JS('', '#[#]', jso, _wrapper);
   }
   var constructor = JS('', '#.constructor', jso)
   var f = null;
   String name;
   bool skip = false;
   while (f == null) {
     name = JS('String', '#.name', constructor);
     f = getHtmlCreateFunction(name);
     if (f == null) {
-      console.error('Could not instantiate $name');
+      console.warn('Could not instantiate $name');
       skip = true;
       constructor = JS('', '#.__proto__', constructor);
     }
   }
   if (skip) {
     console.info('Instantiated $name instead');
   }
   var wrapped = f();
   wrapped.raw = jso;
   JS('', '#[#] = #', jso, _wrapper, wrapped);
@@ skipping 121 matching lines @@
   return null;
 }
 
 Function _getHtmlFunction(String key) {
   if (htmlBlinkFunctionMap.containsKey(key)) {
     return htmlBlinkFunctionMap[key]();
   }
   return null;
 }