bindings: Use an alias for @@iterator in certain declarations.

third_party/WebKit/Source/core/css/FontFaceSet.h

Index: third_party/WebKit/Source/core/css/FontFaceSet.h
diff --git a/third_party/WebKit/Source/core/css/FontFaceSet.h b/third_party/WebKit/Source/core/css/FontFaceSet.h
index 8e137e3339f794fbf267f47417b7847fb0a6f221..55bd023aa4549c9c836ca09339f48ead6deb34a8 100644
--- a/third_party/WebKit/Source/core/css/FontFaceSet.h
+++ b/third_party/WebKit/Source/core/css/FontFaceSet.h
@@ -52,7 +52,7 @@ class Font;
 class FontFaceCache;
 class ExecutionContext;
 
-using FontFaceSetIterable = PairIterable<Member<FontFace>, Member<FontFace>>;
+using FontFaceSetIterable = SetlikeIterable<Member<FontFace>>;
 
 class CORE_EXPORT FontFaceSet final : public EventTargetWithInlineData,
                                       public Supplement<Document>,
@@ -116,6 +116,7 @@ class CORE_EXPORT FontFaceSet final : public EventTargetWithInlineData,
     return new FontFaceSet(document);
   }
 
+  // Iterable overrides.
   FontFaceSetIterable::IterationSource* StartIteration(
       ScriptState*,
       ExceptionState&) override;