stats.lua: page 2 - frame timing: use fixed display order

Page 2 displays the frame timing info for each type (currently "Fresh"
and "Redraw"), but since they're unordered keys of a map, their
iteration order and hence their order on screen could (and did) change
depending on $things, which was annoying.

haasn thinks none of them should be considered more important (and
therefore maybe worthy of being displayed on top), so we go with
lexicographic order, which currently means that "Fresh" is first.

Fixes #9901

player/lua/stats.lua

@@ -280,6 +280,14 @@ local function append_property(s, prop, attr, excluded)
     return append(s, ret, attr)
 end
 
+local function sorted_keys(t, comp_fn)
+    local keys = {}
+    for k,_ in pairs(t) do
+        keys[#keys+1] = k
+    end
+    table.sort(keys, comp_fn)
+    return keys
+end
 
 local function append_perfdata(s, dedicated_page)
     local vo_p = mp.get_property_native("vo-passes")
@@ -327,7 +335,8 @@ local function append_perfdata(s, dedicated_page)
                      b("Frame Timings:"), o.prefix_sep, o.font_size * 0.66,
                      "(last/average/peak  μs)", o.font_size)
 
-    for frame, data in pairs(vo_p) do
+    for _,frame in ipairs(sorted_keys(vo_p)) do  -- ensure fixed display order
+        local data = vo_p[frame]
         local f = "%s%s%s{\\fn%s}%s / %s / %s %s%s{\\fn%s}%s%s%s"
 
         if dedicated_page then