Release graphics resources properly.

vtkScalarBarActor wasn't releasing graphics resources for internal texture. This
fixes the problem.

Change-Id: I5f01c7d8ad0f78c25b4ab8f21bc8b4e66ae91c5f

Rendering/Annotation/vtkScalarBarActor.cxx

@@ -266,6 +266,7 @@ void vtkScalarBarActor::ReleaseGraphicsResources(vtkWindow* win)
   this->P->AnnotationLeadersActor->ReleaseGraphicsResources(win);
   this->BackgroundActor->ReleaseGraphicsResources(win);
   this->FrameActor->ReleaseGraphicsResources(win);
+  this->Texture->ReleaseGraphicsResources(win);
 }
 
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