fix this-before-super checking (see #10193)

extra/CHANGES.txt

@@ -9,6 +9,7 @@
 	hl : fixed debugging of `catch` blocks (#10109)
 	jvm : fixed manifest generation for cases with a lot of jar libraries (#10157)
 	js : fixed extending extern classes for es5 (#10192)
+	js : fixed checking `this` before `super` for es6 (#10193)
 
 2021-02-26 4.2.1:
 

src/typing/typeloadFunction.ml

@@ -154,7 +154,7 @@ let type_function ctx (args : function_arguments) ret fmode e do_display p =
 					{ e with eexpr = TBlock (ev :: l) }
 				else begin
 					let rec has_v e = match e.eexpr with
-						| TLocal v' when v == v -> true
+						| TLocal v' when v' == v -> true
 						| _ -> check_expr has_v e
 					in
 					let rec loop el = match el with