Model each Dart library as its own ScriptState when devtools are enabled.

Source/bindings/v8/ScriptState.h

Index: Source/bindings/v8/ScriptState.h
diff --git a/Source/bindings/v8/ScriptState.h b/Source/bindings/v8/ScriptState.h
index 16a4a4a5ccbc16338997adda8e4a8896f34b2b53..4b54199227e45ea9b8cd3014de4bb8566ec9eeba 100644
--- a/Source/bindings/v8/ScriptState.h
+++ b/Source/bindings/v8/ScriptState.h
@@ -35,6 +35,7 @@
 #include "bindings/v8/V8Utilities.h"
 #include <v8.h>
 #include "wtf/Noncopyable.h"
+#include "wtf/text/WTFString.h"
 
 namespace WebCore {
 
@@ -70,6 +71,10 @@ public:
     bool evalEnabled() const;
     void setEvalEnabled(bool);
 
+    virtual const String* name() { return 0; }
+    // FIXME: determine a better name and use an enum of supported languages, etc.
+    virtual bool isJavaScript() { return true; }
+
     static ScriptState* forContext(v8::Handle<v8::Context>);
     static ScriptState* current();
 
@@ -79,11 +84,12 @@ protected:
     {
     }
 
-    ~ScriptState();
+    explicit ScriptState(v8::Handle<v8::Context>);
+
+    virtual ~ScriptState();
 
 private:
     friend ScriptState* mainWorldScriptState(Frame*);
-    explicit ScriptState(v8::Handle<v8::Context>);
 
     static void makeWeakCallback(v8::Isolate*, v8::Persistent<v8::Context>*, ScriptState*);