ValueSerializer: Add SetTreatArrayBufferViewsAsHostObjects() flag

test/unittests/value-serializer-unittest.cc

Index: test/unittests/value-serializer-unittest.cc
diff --git a/test/unittests/value-serializer-unittest.cc b/test/unittests/value-serializer-unittest.cc
index 2a57ab38e5092bf0d7f40b0019436f6cbabbd2e5..ab1527330aa3953c70f1ac0171fe9bf8d061acc5 100644
--- a/test/unittests/value-serializer-unittest.cc
+++ b/test/unittests/value-serializer-unittest.cc
@@ -2537,6 +2537,35 @@ TEST_F(ValueSerializerTestWithHostObject, RoundTripSameObject) {
       });
 }
 
+class ValueSerializerTestWithHostArrayBufferView
+    : public ValueSerializerTestWithHostObject {
+ protected:
+  void BeforeEncode(ValueSerializer* serializer) override {
+    serializer_ = serializer;

[jbroman, 2017/02/16 23:10:03]

nit: prefer to call the superclass method rather than duplicate it:

ValueSerializerTestWithHostObject::BeforeEncode(serializer);

[Anna Henningsen, 2017/02/17 12:22:55]

Done.

+    serializer_->SetTreatArrayBufferViewsAsHostObjects(true);
+  }
+};
+
+TEST_F(ValueSerializerTestWithHostArrayBufferView, RoundTripUint8ArrayInput) {
+  EXPECT_CALL(serializer_delegate_, WriteHostObject(isolate(), _))
+      .WillOnce(Invoke([this](Isolate*, Local<Object> object) {

[jbroman, 2017/02/16 23:10:03]

nit: EXPECT_TRUE(object->IsUint8Array());

Maybe also confirm that it has the right data, though that may be overkill.

[Anna Henningsen, 2017/02/17 12:22:55]

Done, except for the second part... I can do that if you want but it might just
distract from the point here. :)

+        WriteExampleHostObjectTag();
+        return Just(true);
+      }));
+  EXPECT_CALL(deserializer_delegate_, ReadHostObject(isolate()))
+      .WillOnce(Invoke([this](Isolate*) {
+        EXPECT_TRUE(ReadExampleHostObjectTag());
+        return NewHostObject(deserialization_context(), 0, nullptr);

[jbroman, 2017/02/16 23:10:03]

nit: it's a little weird to produce an entirely different kind of object, even
though that is of course possible. Maybe produce a Uint8Array instead?

[Anna Henningsen, 2017/02/17 12:22:55]

Done.

+      }));
+  RoundTripTest(
+      "({ a: new Uint8Array([1, 2, 3]), get b() { return this.a; }})",
+      [this](Local<Value> value) {
+        EXPECT_TRUE(EvaluateScriptForResultBool(
+            "result.a instanceof ExampleHostObject"));
+        EXPECT_TRUE(EvaluateScriptForResultBool("result.a === result.b"));
+      });
+}
+
 // It's expected that WebAssembly has more exhaustive tests elsewhere; this
 // mostly checks that the logic to embed it in structured clone serialization
 // works correctly.