DevTools: [CSS] setStyleSheetText to work with inline stylesheets.

Source/core/inspector/InspectorCSSAgent.cpp

 /*
  * Copyright (C) 2010, 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
  *     notice, this list of conditions and the following disclaimer in the
@@ skipping 1010 matching lines @@
     InspectorStyleSheet* inspectorStyleSheet = assertStyleSheetForId(errorString, styleSheetId);
     if (!inspectorStyleSheet)
         return;
 
     inspectorStyleSheet->getText(result);
 }
 
 void InspectorCSSAgent::setStyleSheetText(ErrorString* errorString, const String& styleSheetId, const String& text)
 {
     InspectorStyleSheet* inspectorStyleSheet = assertStyleSheetForId(errorString, styleSheetId);
-    if (!inspectorStyleSheet)
+    if (!inspectorStyleSheet) {
+        *errorString = "Style sheet with id " + styleSheetId + " not found.";
         return;
+    }
 
     TrackExceptionState exceptionState;
     m_domAgent->history()->perform(adoptPtr(new SetStyleSheetTextAction(inspectorStyleSheet, text)), exceptionState);
     *errorString = InspectorDOMAgent::toErrorString(exceptionState);
 }
 
 void InspectorCSSAgent::setPropertyText(ErrorString* errorString, const RefPtr<JSONObject>& fullStyleId, int propertyIndex, const String& text, bool overwrite, RefPtr<TypeBuilder::CSS::CSSStyle>& result)
 {
     InspectorCSSId compoundId(fullStyleId);
     ASSERT(!compoundId.isEmpty());
@@ skipping 577 matching lines @@
             documentsToChange.add(element->ownerDocument());
     }
 
     m_nodeIdToForcedPseudoState.clear();
     for (HashSet<Document*>::iterator it = documentsToChange.begin(), end = documentsToChange.end(); it != end; ++it)
         (*it)->setNeedsStyleRecalc(SubtreeStyleChange);
 }
 
 } // namespace WebCore