Revert "Nav: Fixed RenderNavHighlight() clipping, essentially revert 6ea90af6b7. (#787)"

This reverts commit 03f5cd6ca1.

imgui.cpp

@@ -4159,6 +4159,7 @@ void ImGui::RenderNavHighlight(const ImRect& bb, ImGuiID id, ImGuiNavHighlightFl
     ImGuiWindow* window = ImGui::GetCurrentWindow();
 
     ImRect display_rect = bb;
+    display_rect.ClipWith(window->ClipRect);
     if (flags & ImGuiNavHighlightFlags_TypeDefault)
     {
         const float THICKNESS = 2.0f;