toImplArguments should return HeapVector for Union types.

Source/bindings/core/v8/V8Binding.h

Index: Source/bindings/core/v8/V8Binding.h
diff --git a/Source/bindings/core/v8/V8Binding.h b/Source/bindings/core/v8/V8Binding.h
index e6326f405052770dd3f4676d6be900cf3aa858c6..1e3c867b3c3c7134403e27a891b05342e497cfb9 100644
--- a/Source/bindings/core/v8/V8Binding.h
+++ b/Source/bindings/core/v8/V8Binding.h
@@ -804,18 +804,19 @@ VectorType toImplArray(const Vector<ScriptValue>& value, v8::Isolate* isolate, E
     return result;
 }
 
-template <typename T>
-Vector<T> toImplArguments(const v8::FunctionCallbackInfo<v8::Value>& info, int startIndex, ExceptionState& exceptionState)
+template <typename VectorType>
+VectorType toImplArguments(const v8::FunctionCallbackInfo<v8::Value>& info, int startIndex, ExceptionState& exceptionState)
 {
-    Vector<T> result;
-    typedef NativeValueTraits<T> TraitsType;
+    VectorType result;
+    typedef typename VectorType::ValueType ValueType;
+    typedef NativeValueTraits<ValueType> TraitsType;
     int length = info.Length();
     if (startIndex < length) {
         result.reserveInitialCapacity(length - startIndex);
         for (int i = startIndex; i < length; ++i) {
             result.uncheckedAppend(TraitsType::nativeValue(info.GetIsolate(), info[i], exceptionState));
             if (exceptionState.hadException())
-                return Vector<T>();
+                return VectorType();
         }
     }
     return result;