[binding] Replace [CustomIndexedGetter] attributes with [Custom] getter

Source/core/html/HTMLOptionsCollection.idl

Index: Source/core/html/HTMLOptionsCollection.idl
diff --git a/Source/core/html/HTMLOptionsCollection.idl b/Source/core/html/HTMLOptionsCollection.idl
index 84ae0f4711865a3bd6fcec4e61e72742387bde0f..6747e90b612b35735ac5c4d6daaa64a849f84c01 100644
--- a/Source/core/html/HTMLOptionsCollection.idl
+++ b/Source/core/html/HTMLOptionsCollection.idl
@@ -19,13 +19,13 @@
  */
 
 [
-    CustomIndexedSetter,
     GenerateIsReachable=ownerNode,
     DependentLifetime
 ] interface HTMLOptionsCollection : HTMLCollection {
     attribute long selectedIndex;
     [CustomSetter, SetterRaisesException] attribute unsigned long length;
     [ImplementedAs=item] getter Node(unsigned long index);
+    [Custom] setter boolean (unsigned long index, Node value);
     [ImplementedAs=anonymousNamedGetter] getter (NodeList or Node)(DOMString name);
 
     [Custom] Node namedItem([Default=Undefined] optional DOMString name);