LibJS: Convert new_private_environment() to NonnullGCPtr

Userland/Libraries/LibJS/AST.cpp

@@ -1852,7 +1852,7 @@ ThrowCompletionOr<ECMAScriptFunctionObject*> ClassExpression::class_definition_e
         MUST(class_environment->create_immutable_binding(vm, binding_name, true));
 
     auto* outer_private_environment = vm.running_execution_context().private_environment;
-    auto* class_private_environment = new_private_environment(vm, outer_private_environment);
+    auto class_private_environment = new_private_environment(vm, outer_private_environment);
 
     for (auto const& element : m_elements) {
         auto opt_private_name = element.private_bound_identifier();

Userland/Libraries/LibJS/Runtime/AbstractOperations.cpp

@@ -435,7 +435,7 @@ NonnullGCPtr<FunctionEnvironment> new_function_environment(ECMAScriptFunctionObj
 }
 
 // 9.2.1.1 NewPrivateEnvironment ( outerPrivEnv ), https://tc39.es/ecma262/#sec-newprivateenvironment
-PrivateEnvironment* new_private_environment(VM& vm, PrivateEnvironment* outer)
+NonnullGCPtr<PrivateEnvironment> new_private_environment(VM& vm, PrivateEnvironment* outer)
 {
     // 1. Let names be a new empty List.
     // 2. Return the PrivateEnvironment Record { [[OuterPrivateEnvironment]]: outerPrivEnv, [[Names]]: names }.

Userland/Libraries/LibJS/Runtime/AbstractOperations.h

@@ -22,7 +22,7 @@ namespace JS {
 NonnullGCPtr<DeclarativeEnvironment> new_declarative_environment(Environment&);
 NonnullGCPtr<ObjectEnvironment> new_object_environment(Object&, bool is_with_environment, Environment*);
 NonnullGCPtr<FunctionEnvironment> new_function_environment(ECMAScriptFunctionObject&, Object* new_target);
-PrivateEnvironment* new_private_environment(VM& vm, PrivateEnvironment* outer);
+NonnullGCPtr<PrivateEnvironment> new_private_environment(VM& vm, PrivateEnvironment* outer);
 Environment& get_this_environment(VM&);
 bool can_be_held_weakly(Value);
 Object* get_super_constructor(VM&);