IDL: Clean up argument conversion error handling

Source/bindings/templates/methods.cpp

 {##############################################################################}
 {% macro generate_method(method, world_suffix) %}
 {% filter conditional(method.conditional_string) %}
 static void {{method.name}}{{method.overload_index}}Method{{world_suffix}}(const v8::FunctionCallbackInfo<v8::Value>& info)
 {
     {# Local variables #}
     {% if method.has_exception_state %}
     ExceptionState exceptionState(ExceptionState::ExecutionContext, "{{method.name}}", "{{interface_name}}", info.Holder(), info.GetIsolate());
     {% endif %}
     {# Overloaded methods have length checked during overload resolution #}
@@ skipping 45 matching lines @@
 {% endfilter %}
 {% endmacro %}
 
 
 {######################################}
 {% macro generate_arguments(method, world_suffix) %}
 {% for argument in method.arguments %}
 {{generate_argument_var_declaration(argument)}};
 {% endfor %}
 {
-    {% if method.arguments_need_try_catch %}
-    v8::TryCatch block;
-    V8RethrowTryCatchScope rethrow(block);
-    {% endif %}
     {% for argument in method.arguments %}
     {% if argument.default_value %}
     if (!info[{{argument.index}}]->IsUndefined()) {
         {{generate_argument(method, argument, world_suffix) | indent(8)}}
     } else {
         {{argument.name}} = {{argument.default_value}};
     }
     {% else %}
     {{generate_argument(method, argument, world_suffix) | indent}}
     {% endif %}
@@ skipping 540 matching lines @@
   if method.is_per_world_bindings else '0' %}
 {% set property_attribute =
   'static_cast<v8::PropertyAttribute>(%s)' % ' | '.join(method.property_attributes)
   if method.property_attributes else 'v8::None' %}
 {% set only_exposed_to_private_script = 'V8DOMConfiguration::OnlyExposedToPrivateScript' if method.only_exposed_to_private_script else 'V8DOMConfiguration::ExposedToAllScripts' %}
 static const V8DOMConfiguration::MethodConfiguration {{method.name}}MethodConfiguration = {
     "{{method.name}}", {{method_callback}}, {{method_callback_for_main_world}}, {{method.length}}, {{only_exposed_to_private_script}},
 };
 V8DOMConfiguration::installMethod({{method.function_template}}, {{method.signature}}, {{property_attribute}}, {{method.name}}MethodConfiguration, isolate);
 {%- endmacro %}