More informative error messages for non-Transferables.

Source/bindings/v8/custom/V8DedicatedWorkerGlobalScopeCustom.cpp

Index: Source/bindings/v8/custom/V8DedicatedWorkerGlobalScopeCustom.cpp
diff --git a/Source/bindings/v8/custom/V8DedicatedWorkerGlobalScopeCustom.cpp b/Source/bindings/v8/custom/V8DedicatedWorkerGlobalScopeCustom.cpp
index ffa25a147a0b9f0e3bbc5aef81f5d19e157e8cbb..4743935860fef9b4ba7d5be6feb2a2e201876381 100644
--- a/Source/bindings/v8/custom/V8DedicatedWorkerGlobalScopeCustom.cpp
+++ b/Source/bindings/v8/custom/V8DedicatedWorkerGlobalScopeCustom.cpp
@@ -46,7 +46,8 @@ void V8DedicatedWorkerGlobalScope::postMessageMethodCustom(const v8::FunctionCal
     MessagePortArray ports;
     ArrayBufferArray arrayBuffers;
     if (args.Length() > 1) {
-        if (!extractTransferables(args[1], ports, arrayBuffers, args.GetIsolate()))
+        if (!extractTransferables(args[1], ports, arrayBuffers,
+            args.GetIsolate(), "Second argument is not a sequence type"))

[Mike West, 2013/10/21 06:51:22]

Two things:

1. Can you bring in ExceptionMessages here? Something like
"ExceptionMessages::failedToExecute("postMessage", "WorkerGlobalScope", ...)"
would generate a friendlier error message.

2. I'd prefer to use something more clear than "sequence type". Developers don't
read IDL (and, honestly, I had to go find the IDL spec to understand what this
meant. :) ). I'd suggest something like "The second argument ('transfer') is
neither an array, nor does it support indexed properties."

             return;
     }
     bool didThrow = false;