Added a console warning when <picture><source src></picture> is used.

Source/core/frame/UseCounter.cpp

 
 /*
  * Copyright (C) 2012 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 767 matching lines @@
 
     case WebSocketURL:
         return "'WebSocket.URL' is deprecated. Please use 'WebSocket.url' instead.";
 
     case HTMLTableElementVspace:
         return "The 'vspace' attribute on table is deprecated. Please use CSS instead.";
 
     case HTMLTableElementHspace:
         return "The 'hspace' attribute on table is deprecated. Please use CSS instead.";
 
+    case PictureSourceSrc:
+        return "<source src> with a <picture> parent is invalid and therefore ignored. Please use <source srcset> instead.";
+
     // Features that aren't deprecated don't have a deprecation message.
     default:
         return String();
     }
 }
 
 void UseCounter::count(CSSParserContext context, CSSPropertyID feature)
 {
     ASSERT(feature >= firstCSSProperty);
     ASSERT(feature <= lastCSSProperty);
@@ skipping 28 matching lines @@
 UseCounter* UseCounter::getFrom(const StyleSheetContents* sheetContents)
 {
     // FIXME: We may want to handle stylesheets that have multiple owners
     //        http://crbug.com/242125
     if (sheetContents && sheetContents->hasSingleOwnerNode())
         return getFrom(sheetContents->singleOwnerDocument());
     return 0;
 }
 
 } // namespace blink