LibJS: Mark JS::Cell::initialize() as MUST_UPCALL

Intermediate classes in the initialize() chain set up prototypes and
define properties. Forgetting to call Base::initialize() in any
override would silently skip that setup.

Libraries/LibJS/Heap/Cell.h

@@ -17,7 +17,7 @@ class JS_API Cell : public GC::Cell {
     GC_CELL(Cell, GC::Cell);
 
 public:
-    virtual void initialize(Realm&);
+    MUST_UPCALL virtual void initialize(Realm&);
 
     virtual bool is_generator_result() const { return false; }
     virtual bool is_environment() const { return false; }

Libraries/LibJS/Runtime/Intl/CollatorCompareFunction.cpp

@@ -24,8 +24,9 @@ CollatorCompareFunction::CollatorCompareFunction(Realm& realm, Collator& collato
 {
 }
 
-void CollatorCompareFunction::initialize(Realm&)
+void CollatorCompareFunction::initialize(Realm& realm)
 {
+    Base::initialize(realm);
     auto& vm = this->vm();
     define_direct_property(vm.names.length, Value(2), Attribute::Configurable);
     define_direct_property(vm.names.name, PrimitiveString::create(vm, String {}), Attribute::Configurable);

Libraries/LibJS/Runtime/Object.cpp

@@ -99,8 +99,9 @@ Object::~Object()
         s_intrinsics.remove(this);
 }
 
-void Object::initialize(Realm&)
+void Object::initialize(Realm& realm)
 {
+    Base::initialize(realm);
 }
 
 void Object::unsafe_set_shape(Shape& shape)

Libraries/LibJS/Runtime/Set.cpp

@@ -24,6 +24,7 @@ Set::Set(Object& prototype)
 
 void Set::initialize(Realm& realm)
 {
+    Base::initialize(realm);
     m_values = Map::create(realm);
 }
 

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

@@ -3487,6 +3487,7 @@ GC_DEFINE_ALLOCATOR(@named_properties_class@);
 
 void @named_properties_class@::initialize(JS::Realm& realm)
 {
+    Base::initialize(realm);
     auto& vm = realm.vm();
 
     // The class string of a named properties object is the concatenation of the interface's identifier and the string "Properties".