Export assignment expression must not track variables (#4660)

Only export the result of the assignment expression. This value cannot be changed later.

JerryScript-DCO-1.0-Signed-off-by: Zoltan Herczeg zherczeg.u-szeged@partner.samsung.com

tests/jerry/es.next/module-export-default-main.mjs

@@ -21,6 +21,7 @@ import foo6 from "./module-export-default-6.mjs"
 import foo7 from "./module-export-default-7.mjs"
 import foo8, { counter as bar8 } from "./module-export-default-8.mjs"
 import foo9, { counter as bar9 } from "./module-export-default-9.mjs"
+import foo10, { g as bar10 } from "./module-export-default-10.mjs"
 
 let async_queue_expected = ["foo2", "foo3", "foo6", "foo7"];
 let async_queue = [];
@@ -66,6 +67,13 @@ let async_queue = [];
   assert(bar9 === 9.1);
 })();
 
+(function() {
+  var o = {}
+  assert(foo10() === 1.5);
+  assert(bar10(o) === "X");
+  assert(foo10 === o);
+})();
+
 Array.prototype.assertArrayEqual = function(expected) {
   assert(this.length === expected.length);
   print(this);