fix #4488

Author: bobzhang

jscomp/core/js_dump.ml

@@ -868,7 +868,7 @@ and expression_desc cxt ~(level:int) f x : cxt  =
           | true,  1 -> Js_op.Lit Literals.tl 
           | _ ->
           Js_op.Lit ("_" ^ string_of_int i)) , e )
-          (if !Js_config.debug then 
+          (if !Js_config.debug && not is_cons then 
              [name_symbol, E.str p.name]
            else []) in         
       if p.num_nonconst = 1 then       

jscomp/test/debug_mode_value.js

@@ -7,5 +7,11 @@ var u = {
   [Symbol.for("name")]: "A"
 };
 
+var h = {
+  hd: 1,
+  tl: /* [] */0
+};
+
 exports.u = u;
+exports.h = h;
 /* No side effect */

jscomp/test/debug_mode_value.ml

@@ -12,3 +12,4 @@
 type t = A of int * int 
 
 let u  = A (1,2)
+let h = [1]