IDL: Support runtime enabled overloads affecting Function.length

Source/bindings/templates/interface_base.cpp

Index: Source/bindings/templates/interface_base.cpp
diff --git a/Source/bindings/templates/interface_base.cpp b/Source/bindings/templates/interface_base.cpp
index 6d8b00a188fb9e9007024b9355b186e797a359a2..da5efd51f5a364a98cead3f8fb0eb5173d4a9547 100644
--- a/Source/bindings/templates/interface_base.cpp
+++ b/Source/bindings/templates/interface_base.cpp
@@ -140,7 +140,7 @@ bool namedSecurityCheck(v8::Local<v8::Object> host, v8::Local<v8::Value> key, v8
 {# Methods #}
 {% from 'methods.cpp' import generate_method, overload_resolution_method,
        method_callback, origin_safe_method_getter, generate_constructor,
-       method_implemented_in_private_script
+       method_implemented_in_private_script, runtime_determined_length_method
        with context %}
 {% for method in methods %}
 {% if method.should_be_exposed_to_script %}
@@ -149,6 +149,9 @@ bool namedSecurityCheck(v8::Local<v8::Object> host, v8::Local<v8::Value> key, v8
 {{generate_method(method, world_suffix)}}
 {% endif %}
 {% if method.overloads and method.overloads.visible %}
+{% if method.overloads.runtime_determined_lengths %}
+{{runtime_determined_length_method(method.overloads)}}
+{% endif %}
 {{overload_resolution_method(method.overloads, world_suffix)}}
 {% endif %}
 {% if not method.overload_index or method.overloads %}