Stub out indexed setter for HTMLOptionsCollection.

Source/WebCore/bindings/dart/custom/DartHTMLOptionsCollectionCustom.cpp

Index: Source/WebCore/bindings/dart/custom/DartHTMLOptionsCollectionCustom.cpp
diff --git a/Source/WebCore/bindings/dart/custom/DartHTMLOptionsCollectionCustom.cpp b/Source/WebCore/bindings/dart/custom/DartHTMLOptionsCollectionCustom.cpp
index 97f5205ed8a877e2d9a1f170d7ef18047e9552f4..6589d5d357e9fe5a1335cd50eefc039c4d570c89 100644
--- a/Source/WebCore/bindings/dart/custom/DartHTMLOptionsCollectionCustom.cpp
+++ b/Source/WebCore/bindings/dart/custom/DartHTMLOptionsCollectionCustom.cpp
@@ -58,6 +58,12 @@ void lengthSetter(Dart_NativeArguments)
     DART_UNIMPLEMENTED();
 }
 
+void numericIndexSetterCallback(Dart_NativeArguments)
+{
+    // FIXME: proper implementation.
+    DART_UNIMPLEMENTED();
+}
+
 }
 
 }