Minor clean up to remove unused instance variable.

Source/Urho3D/Script/ScriptInstance.cpp

@@ -63,7 +63,6 @@ static const char* methodDeclarations[] = {
 
 ScriptInstance::ScriptInstance(Context* context) :
     Component(context),
-    script_(GetSubsystem<Script>()),
     scriptObject_(0),
     subscribed_(false),
     subscribedPostFixed_(false)

Source/Urho3D/Script/ScriptInstance.h

@@ -179,8 +179,6 @@ private:
     /// Handle script file reload finished.
     void HandleScriptFileReloadFinished(StringHash eventType, VariantMap& eventData);
 
-    /// Script subsystem.
-    SharedPtr<Script> script_;
     /// Script file.
     WeakPtr<ScriptFile> scriptFile_;
     /// Script object.