[aux] remove double scaling of capheight from typoascender

Fix #358

The typographic ascender value from the metrics (Windows metrics) table
comes prescaled by the fontloader but we scaled it nevertheless. This is
not true, however, for the value in the metrics table. Fix the access
method to treat the values differently.

src/luaotfload-auxiliary.lua

@@ -212,15 +212,19 @@ end
 
 local query_ascender = function (fontdata)
   local parameters = fontdata.parameters if not parameters then return false end
+  local ascender   = parameters.ascender
+  if ascender then
+    return ascender --- pre-scaled
+  end
+
   local shared     = fontdata.shared     if not shared     then return false end
   local rawdata    = shared.rawdata      if not rawdata    then return false end
   local metadata   = rawdata.metadata    if not metadata   then return false end
-  local ascender   = parameters.ascender
-                  or metadata.ascender   if not ascender   then return false end
+  ascender         = metadata.ascender   if not ascender   then return false end
   local size       = parameters.size     if not size       then return false end
   local units = lookup_units (fontdata)
   if not units or units == 0 then return false end
-  return ascender * size / units
+  return ascender * size / units --- scaled
 end
 
 local query_capheight = function (fontdata)