Worklet: Enable module script loading for main thread worklets

third_party/WebKit/LayoutTests/http/tests/worklet/webexposed/resources/global-interface-listing-worklet.js

Index: third_party/WebKit/LayoutTests/http/tests/worklet/webexposed/resources/global-interface-listing-worklet.js
diff --git a/third_party/WebKit/LayoutTests/http/tests/worklet/webexposed/resources/global-interface-listing-worklet.js b/third_party/WebKit/LayoutTests/http/tests/worklet/webexposed/resources/global-interface-listing-worklet.js
index 0f2ae2ba50a576ce660ab200ba2e0355d8b36370..b602b57bd17b2f2251c81f4c8962dc08a92ca43b 100644
--- a/third_party/WebKit/LayoutTests/http/tests/worklet/webexposed/resources/global-interface-listing-worklet.js
+++ b/third_party/WebKit/LayoutTests/http/tests/worklet/webexposed/resources/global-interface-listing-worklet.js
@@ -1,7 +1,16 @@
 /* Adopted from LayoutTests/webexposed/resources/global-interface-listing.js */
 
 // Run all the code in a local scope.
-(function(global_object) {
+(function() {
+
+// Generally, Worklet should not have a reference to the global object.
+// https://drafts.css-houdini.org/worklets/#code-idempotency
+if (this) {
+  console.error('"this" should not refer to the global object');
+  return;
+}
+// Instead, retrieve the global object in a tricky way.
+var global_object = Function('return this')();
 
 var globals = [];
 
@@ -66,7 +75,7 @@ var js_builtins = new Set([
 function is_web_idl_constructor(property_name) {
   if (js_builtins.has(property_name))
     return false;
-  var descriptor = Object.getOwnPropertyDescriptor(this, property_name);
+  var descriptor = Object.getOwnPropertyDescriptor(global_object, property_name);
   if (descriptor.value === undefined ||
       descriptor.value.prototype === undefined) {
     return false;
@@ -97,13 +106,13 @@ function collect_property_info(object, property_name, output) {
 var interface_names = Object.getOwnPropertyNames(global_object).filter(is_web_idl_constructor);
 interface_names.sort();
 interface_names.forEach(function(interface_name) {
-  var inherits_from = this[interface_name].__proto__.name;
+  var inherits_from = global_object[interface_name].__proto__.name;
   if (inherits_from)
     globals.push('interface ' + interface_name + ' : ' + inherits_from);
   else
     globals.push('interface ' + interface_name);
   // List static properties then prototype properties.
-  [this[interface_name], this[interface_name].prototype].forEach(function(object) {
+  [global_object[interface_name], global_object[interface_name].prototype].forEach(function(object) {
     if ('prototype' in object) {
       // Skip properties that aren't static (e.g. consts), or are inherited.
       var proto_properties = new Set(Object.keys(object.prototype).concat(
@@ -138,4 +147,4 @@ globals.forEach(function(global) {
     console.log(global);
 });
 
-})(this); // Run all the code in a local scope.
+})(); // Run all the code in a local scope.