LibGC: Delete operators ! and bool from GC::Ref

The GC::Ref smart pointer is always non-null, so there's no need for it
to be convertible to bool.

This exposed a small number of unnecessary null checks which we remove.

Libraries/LibGC/Ptr.h

@@ -71,6 +71,9 @@ public:
 
     operator T&() const { return *m_ptr; }
 
+    operator bool() const = delete;
+    bool operator!() const = delete;
+
 private:
     T* m_ptr { nullptr };
 };

Libraries/LibJS/AST.cpp

@@ -322,7 +322,6 @@ ThrowCompletionOr<ECMAScriptFunctionObject*> ClassExpression::create_class_const
     }
 
     auto prototype = Object::create_prototype(realm, proto_parent);
-    VERIFY(prototype);
 
     // FIXME: Step 14.a is done in the parser. By using a synthetic super(...args) which does not call @@iterator of %Array.prototype%
     auto const& constructor = *m_constructor;

Libraries/LibJS/Bytecode/Interpreter.cpp

@@ -1344,7 +1344,6 @@ static Value instantiate_ordinary_function_expression(Interpreter& interpreter,
 
     auto environment = GC::Ref { *interpreter.running_execution_context().lexical_environment };
     if (has_own_name) {
-        VERIFY(environment);
         environment = new_declarative_environment(*environment);
         MUST(environment->create_immutable_binding(interpreter.vm(), own_name, false));
     }