Removed unneeded call to MakeCurrent()

RemoveAllViewProps doesn't call MakeCurrent(), so presumably RemoveViewProp doesn't need to either.

Rendering/Core/vtkViewport.cxx

@@ -152,10 +152,6 @@ void vtkViewport::RemoveViewProp(vtkProp* p)
 {
   if (p && this->HasViewProp(p))
   {
-    if (this->VTKWindow)
-    {
-      this->VTKWindow->MakeCurrent();
-    }
     p->ReleaseGraphicsResources(this->VTKWindow);
     p->RemoveConsumer(this);
     this->Props->RemoveItem(p);