bindings: Make the sequence conversion code more compliant with WebIDL.

third_party/WebKit/Source/bindings/core/v8/V8Binding.h

Index: third_party/WebKit/Source/bindings/core/v8/V8Binding.h
diff --git a/third_party/WebKit/Source/bindings/core/v8/V8Binding.h b/third_party/WebKit/Source/bindings/core/v8/V8Binding.h
index f783f6ab25da629154318713a47ad392a43c46bb..0beb32ac29fe00354deffc1356f3121fcb0e17e3 100644
--- a/third_party/WebKit/Source/bindings/core/v8/V8Binding.h
+++ b/third_party/WebKit/Source/bindings/core/v8/V8Binding.h
@@ -829,6 +829,12 @@ inline bool ToV8Sequence(v8::Local<v8::Value> value,
   length = sequence_length;
   return true;
 }
+// Validates that the passed object is a sequence type per the WebIDL spec: it
+// has a callable @iterator.
+// https://heycam.github.io/webidl/#es-sequence
+CORE_EXPORT bool HasCallableIteratorSymbol(v8::Isolate*,
+                                           v8::Local<v8::Value>,
+                                           ExceptionState&);
 
 // TODO(rakuco): remove the specializations below (and consequently the
 // non-IDLBase version of NativeValueTraitsBase) once we manage to convert all
@@ -895,7 +901,8 @@ struct NativeValueTraits<double> {
 };
 
 template <>
-struct NativeValueTraits<v8::Local<v8::Value>> {
+struct NativeValueTraits<v8::Local<v8::Value>>
+    : public NativeValueTraitsBase<v8::Local<v8::Value>> {
   static inline v8::Local<v8::Value> NativeValue(
       v8::Isolate* isolate,
       v8::Local<v8::Value> value,
@@ -904,15 +911,6 @@ struct NativeValueTraits<v8::Local<v8::Value>> {
   }
 };
 
-template <>
-struct NativeValueTraits<ScriptValue> {
-  static inline ScriptValue NativeValue(v8::Isolate* isolate,
-                                        v8::Local<v8::Value> value,
-                                        ExceptionState& exception_state) {
-    return ScriptValue(ScriptState::Current(isolate), value);
-  }
-};
-
 template <typename T>
 struct NativeValueTraits<Vector<T>> {
   static inline Vector<T> NativeValue(v8::Isolate* isolate,