Warn developers about deprecated features only once per page-load.

Source/devtools/front_end/ConsoleModel.js

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 213 matching lines @@
 WebInspector.ConsoleMessage.MessageSource = {
     XML: "xml",
     JS: "javascript",
     Network: "network",
     ConsoleAPI: "console-api",
     Storage: "storage",
     AppCache: "appcache",
     Rendering: "rendering",
     CSS: "css",
     Security: "security",
-    Other: "other"
+    Other: "other",
+    Deprecation: "deprecation"
 }
 
 WebInspector.ConsoleMessage.MessageType = {
     Log: "log",
     Dir: "dir",
     DirXML: "dirxml",
     Table: "table",
     Trace: "trace",
     Clear: "clear",
     StartGroup: "startGroup",
@@ skipping 56 matching lines @@
     {
         if (!WebInspector.settings.preserveConsoleLog.get())
             this._console.clearMessages();
     }
 }
 
 /**
  * @type {?WebInspector.ConsoleModel}
  */
 WebInspector.console = null;