BindingsGenerator: Handle global interfaces without named properties

DedicatedWorkerGlobalScope is an object with a Global extended
attribute, but does not define any named property getters. This needs to
be handled by setting the prototype chain to:

    DedicatedWorkerGlobalScope
    ^ DedicatedWorkerGlobalScopePrototype
    ^ WorkerGlobalScopePrototype

(This is different from something like Window, where there is an
intermediate WindowProperties object for named properties.)

Previously, we treated the GlobalMixin object as if it was a simple
prototype object, accidentally setting DedicatedWorkerGlobalScope's
prototype to WorkerGlobalScopePrototype. This caused the expression

    self instanceof DedicatedWorkerGlobalScope

to return false inside workers.

This makes us pass many more of the "/xhr/idlharness.any.worker" WPT
tests than before, rather than failing early.

Meta/Lagom/Tools/CodeGenerators/LibWeb/BindingsGenerator/IDLGenerators.cpp

@@ -3189,7 +3189,7 @@ void @class_name@::initialize(JS::Realm& realm)
     set_prototype(realm.intrinsics().object_prototype());
 
 )~~~");
-    } else if (is_global_interface && interface.supports_named_properties()) {
+    } else if (is_global_interface) {
         generator.append(R"~~~(
     set_prototype(&ensure_web_prototype<@prototype_name@>(realm, "@name@"_fly_string));
 )~~~");
@@ -4766,6 +4766,10 @@ void @prototype_class@::initialize(JS::Realm& realm)
             generator.append(R"~~~(
     define_direct_property(vm().well_known_symbol_to_string_tag(), JS::PrimitiveString::create(vm(), "@namespaced_name@"_string), JS::Attribute::Configurable);
     set_prototype(&ensure_web_prototype<@prototype_class@>(realm, "@named_properties_class@"_fly_string));
+)~~~");
+        } else {
+            generator.append(R"~~~(
+    set_prototype(&ensure_web_prototype<@prototype_base_class@>(realm, "@parent_name@"_fly_string));
 )~~~");
         }
         generator.append(R"~~~(

Tests/LibWeb/Text/expected/HTML/DedicatedWorkerGlobalScope-instanceof.txt

@@ -0,0 +1 @@
+PASS

Tests/LibWeb/Text/input/HTML/DedicatedWorkerGlobalScope-instanceof-worker.js

@@ -0,0 +1,5 @@
+onmessage = function (event) {
+    if (event.data === "run") {
+        postMessage({ result: self instanceof DedicatedWorkerGlobalScope });
+    }
+};

Tests/LibWeb/Text/input/HTML/DedicatedWorkerGlobalScope-instanceof.html

@@ -0,0 +1,15 @@
+<script src="../include.js"></script>
+<script>
+    asyncTest(done => {
+        const worker = new Worker("DedicatedWorkerGlobalScope-instanceof-worker.js");
+        worker.onmessage = function (event) {
+            if (event.data.result === true) {
+                println("PASS");
+            } else {
+                println("FAIL");
+            }
+            done();
+        };
+        worker.postMessage("run");
+    });
+</script>