Fix upvalues that allow closures to work properly.

src/test/res/test2.lua

@@ -1,10 +1,29 @@
+
 function sum(a,b,c,d)          -- "sum" method
-  return a+b+c+d   -- return sum
+	local d = d or 0
+	return a+b+c+d   -- return sum
 end
 print( sum( 1, 2, 3, 4 ) )
 print( sum( 5, 6, 7 ) )
 print( sum( 9, 10, 11, 12, 13, 14 ) )
 print( sum( sum(1,2,3,4), sum(5,6,7), sum(9,10,11,12,13,14), 15 ) )
 
+function myfunc(x)
+	return x*x;
+end
 
+print( myfunc(0.1) )
+
+do
+  local oldMyfunc = myfunc
+  local k = 55
+  myfunc = function (x)
+    local a = k + oldMyfunc(x)
+    k = k + 5
+    return a
+  end
+end
+
+print( myfunc(0.1) )
+print( myfunc(0.1) )