Frustum-cull small draws

Some games do a poor job of culling stuff, and some transparent
sprites can be very expensive if they cause a copy.
Skipping them if outside the viewport makes sense in that case.

One example are the flame sprites in #17797 .

Additionally, we should be able to cull through-mode draws easily, this
one doesn't even try.

Common/UI/View.cpp

@@ -620,7 +620,6 @@ CollapsibleHeader::CollapsibleHeader(bool *toggle, const std::string &text, Layo
 
 void CollapsibleHeader::Draw(UIContext &dc) {
 	Style style = dc.theme->itemStyle;
-	style.background.color = 0;
 	if (HasFocus()) style = dc.theme->itemFocusedStyle;
 	if (down_) style = dc.theme->itemDownStyle;
 	if (!IsEnabled()) style = dc.theme->itemDisabledStyle;