Make ScriptStreamer and dependents Oilpan friendly.

Source/core/inspector/InspectorDebuggerAgent.h

Index: Source/core/inspector/InspectorDebuggerAgent.h
diff --git a/Source/core/inspector/InspectorDebuggerAgent.h b/Source/core/inspector/InspectorDebuggerAgent.h
index 1834d0e504d6656937030084e4af00397c6820b0..a0be46e2b089ee0a2b43ece91b3dfbad7f9062d9 100644
--- a/Source/core/inspector/InspectorDebuggerAgent.h
+++ b/Source/core/inspector/InspectorDebuggerAgent.h
@@ -30,6 +30,7 @@
 #ifndef InspectorDebuggerAgent_h
 #define InspectorDebuggerAgent_h
 
+#include "bindings/core/v8/Nullable.h"
 #include "bindings/core/v8/ScriptState.h"
 #include "bindings/core/v8/ScriptValue.h"
 #include "core/InspectorFrontend.h"
@@ -91,7 +92,7 @@ public:
     void addMessageToConsole(ConsoleMessage*);
 
     String preprocessEventListener(LocalFrame*, const String& source, const String& url, const String& functionName);
-    PassOwnPtr<ScriptSourceCode> preprocess(LocalFrame*, const ScriptSourceCode&);
+    Nullable<ScriptSourceCode> preprocess(LocalFrame*, const ScriptSourceCode&);
 
     // Part of the protocol.
     void enable(ErrorString*) final;