LibJS: Make Cell::initialize() return void

Stop worrying about tiny OOMs.

Work towards #20405

Userland/Libraries/LibWeb/HTML/HTMLMetaElement.h

@@ -38,7 +38,7 @@ public:
 private:
     HTMLMetaElement(DOM::Document&, DOM::QualifiedName);
 
-    virtual JS::ThrowCompletionOr<void> initialize(JS::Realm&) override;
+    virtual void initialize(JS::Realm&) override;
 
     // ^DOM::Element
     virtual void inserted() override;