DevTools: nits: introduce a handy asBool(bool*) and use across agents.

Source/core/inspector/InspectorBaseAgent.h

 /*
  * 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 91 matching lines @@
     {
         dispatcher->registerAgent(static_cast<T*>(this));
     }
 
 protected:
     explicit InspectorBaseAgent(const String& name) : InspectorAgent(name)
     {
     }
 };
 
+inline bool asBool(const bool* const b, bool defaultValue = false)
+{
+    return b ? *b : defaultValue;
+}
+
 } // namespace blink
 
 #endif // !defined(InspectorBaseAgent_h)