Fix the tests after my previous commit.

This actually makes [Named] work, previously it was
generating invalid dart.

TBR=abarth@chromium.org
BUG=

Review URL: https://codereview.chromium.org/931273002

engine/bindings/scripts/templates/interface_dart.template

@@ -11,7 +11,7 @@ part of sky.core;
         {{ '{' if arg.is_named else '[' }}
         {%- endif -%}
         {{ arg.dart_type }} {{ arg.name }}
-        {%- if arg.is_optional %} = {{ arg.dart_default_value }}
+        {%- if arg.is_optional %} {{ ':' if arg.is_named else '='}}  {{ arg.dart_default_value }}
         {#- TODO(eseidel): This does not support having both optional and named arguments! -#}
         {%- if loop.last -%}{{ '}' if arg.is_named else ']' }}{%- endif -%}
         {%- endif -%}

engine/core/dom/shadow/ShadowRoot.idl

@@ -27,7 +27,7 @@
 interface ShadowRoot : DocumentFragment {
     readonly attribute Element activeElement;
 
-    [RaisesException] Node cloneNode([Default=Undefined] optional boolean deep);
+    [RaisesException] Node cloneNode([Named] optional boolean deep = true);
     Selection getSelection();
     Element getElementById([Default=Undefined] optional DOMString elementId);