Fix attributes of length property for function objects (#3570)

fix length property of function objects to be configurable (ECMA-262 v6, 19.2.4.1)

JerryScript-DCO-1.0-Signed-off-by: HyukWoo Park hyukwoo.park@samsung.com

tests/jerry/es2015/length-property.js

@@ -100,3 +100,24 @@ var builtin_typedArrays = [
     assert(ta.hasOwnProperty('length') === false);
   }
 })();
+
+(function () {
+  /* test length property of function objects */
+  var normal_func = function () {};
+  var arrow_func = () => {};
+
+  var functions = [normal_func, arrow_func];
+
+  for (func of functions) {
+    var desc = Object.getOwnPropertyDescriptor(func, 'length');
+    assert(desc.writable === false);
+    assert(desc.enumerable === false);
+    assert(desc.configurable === true);
+  }
+
+  for (func of functions) {
+    assert(func.hasOwnProperty('length') === true);
+    assert(delete func.length);
+    assert(func.hasOwnProperty('length') === false);
+  }
+})();

tests/jerry/es2015/regression-test-issue-3267.js

@@ -14,7 +14,7 @@
 
 var hasProp = $ => { }
 Object.preventExtensions(hasProp);
-assert (Object.isSealed(hasProp));
+assert (Object.isSealed(hasProp) === false);
 
 var keys = Object.getOwnPropertyNames(hasProp);
 assert (keys.length === 1);

tests/jerry/es2015/regression-test-issue-3536.js

@@ -16,7 +16,7 @@ class A {
   constructor() {
     var hasProp = $ => {}
     Object.preventExtensions(hasProp);
-    assert(Object.isSealed(hasProp) === true);
+    assert(Object.isSealed(hasProp) === false);
   }
   super() {
     $: $