ASP.NET broken rendering of Validation client side code in Firefox

<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" ErrorMessage="Text is Required" ControlToValidate="TextBox1"></asp:RequiredFieldValidator>
<asp:Button ID="btnSubmit" runat="server" Text="Submit" />