LibWeb: Add MathML Namespace to IDL Generator

This will make the codegen produce code for MathML IDL that doesn't
fail to compile in confusing ways.

Meta/Lagom/Tools/CodeGenerators/LibWeb/BindingsGenerator/Namespaces.h

@@ -25,6 +25,7 @@ static constexpr Array libweb_interface_namespaces = {
     "HighResolutionTime"sv,
     "Internals"sv,
     "IntersectionObserver"sv,
+    "MathML"sv,
     "NavigationTiming"sv,
     "RequestIdleCallback"sv,
     "ResizeObserver"sv,