LibJS: Add bytecode generation for FunctionExpression :^)

Userland/Libraries/LibJS/AST.h

@@ -308,6 +308,8 @@ public:
     bool cannot_auto_rename() const { return m_cannot_auto_rename; }
     void set_cannot_auto_rename() { m_cannot_auto_rename = true; }
 
+    virtual void generate_bytecode(Bytecode::Generator&) const override;
+
 private:
     bool m_cannot_auto_rename { false };
 };

Userland/Libraries/LibJS/Bytecode/ASTCodegen.cpp

@@ -605,6 +605,11 @@ void FunctionDeclaration::generate_bytecode(Bytecode::Generator&) const
 {
 }
 
+void FunctionExpression::generate_bytecode(Bytecode::Generator& generator) const
+{
+    generator.emit<Bytecode::Op::NewFunction>(*this);
+}
+
 void VariableDeclaration::generate_bytecode(Bytecode::Generator& generator) const
 {
     for (auto& declarator : m_declarations) {

Userland/Libraries/LibJS/Bytecode/Op.cpp

@@ -218,7 +218,7 @@ void Call::execute(Bytecode::Interpreter& interpreter) const
 void NewFunction::execute(Bytecode::Interpreter& interpreter) const
 {
     auto& vm = interpreter.vm();
-    interpreter.accumulator() = ScriptFunction::create(interpreter.global_object(), m_function_node.name(), m_function_node.body(), m_function_node.parameters(), m_function_node.function_length(), vm.current_scope(), m_function_node.is_generator(), m_function_node.is_strict_mode());
+    interpreter.accumulator() = ScriptFunction::create(interpreter.global_object(), m_function_node.name(), m_function_node.body(), m_function_node.parameters(), m_function_node.function_length(), vm.current_scope(), m_function_node.is_generator(), m_function_node.is_strict_mode(), m_function_node.is_arrow_function());
 }
 
 void Return::execute(Bytecode::Interpreter& interpreter) const