More informative error messages for non-Transferables.

Source/bindings/v8/custom/V8WorkerCustom.cpp

Index: Source/bindings/v8/custom/V8WorkerCustom.cpp
diff --git a/Source/bindings/v8/custom/V8WorkerCustom.cpp b/Source/bindings/v8/custom/V8WorkerCustom.cpp
index 01bcdd8dc9bb0c5fe510597043eb5807ab42393d..d4d6a9f9c3caa39646cadc2aa2b036f4ddcb994a 100644
--- a/Source/bindings/v8/custom/V8WorkerCustom.cpp
+++ b/Source/bindings/v8/custom/V8WorkerCustom.cpp
@@ -31,6 +31,7 @@
 #include "config.h"
 #include "V8Worker.h"
 
+#include "bindings/v8/ExceptionMessages.h"
 #include "bindings/v8/ExceptionState.h"
 #include "bindings/v8/SerializedScriptValue.h"
 #include "bindings/v8/V8Binding.h"
@@ -47,8 +48,12 @@ void V8Worker::postMessageMethodCustom(const v8::FunctionCallbackInfo<v8::Value>
     MessagePortArray ports;
     ArrayBufferArray arrayBuffers;
     if (args.Length() > 1) {
-        if (!extractTransferables(args[1], ports, arrayBuffers, args.GetIsolate()))
+        bool notASequence = false;
+        if (!extractTransferables(args[1], ports, arrayBuffers, notASequence, args.GetIsolate())) {
+            if (notASequence)
+                throwTypeError(ExceptionMessages::failedToExecute("postMessage", "Worker", ExceptionMessages::notASequenceType("Second")), args.GetIsolate());
             return;
+        }
     }
     bool didThrow = false;
     RefPtr<SerializedScriptValue> message =