More informative error messages for non-Transferables.

Source/bindings/v8/V8Binding.h

Index: Source/bindings/v8/V8Binding.h
diff --git a/Source/bindings/v8/V8Binding.h b/Source/bindings/v8/V8Binding.h
index d00ee43e8b3c5cb55fd7930df88ecd1f23e4280c..da51dd8fd028d2dfcd764278f77c97cb94d23395 100644
--- a/Source/bindings/v8/V8Binding.h
+++ b/Source/bindings/v8/V8Binding.h
@@ -75,7 +75,7 @@ namespace WebCore {
 
     v8::ArrayBuffer::Allocator* v8ArrayBufferAllocator();
 
-    v8::Handle<v8::Value> toV8Sequence(v8::Handle<v8::Value>, uint32_t& length, v8::Isolate*);
+    v8::Handle<v8::Value> toV8Sequence(v8::Handle<v8::Value>, uint32_t& length, bool* notASequence, v8::Isolate*);
 
     inline v8::Handle<v8::Value> argumentOrNull(const v8::FunctionCallbackInfo<v8::Value>& args, int index)
     {
@@ -450,7 +450,7 @@ namespace WebCore {
         uint32_t length = 0;
         if (value->IsArray())
             length = v8::Local<v8::Array>::Cast(v8Value)->Length();
-        else if (toV8Sequence(value, length, isolate).IsEmpty())
+        else if (toV8Sequence(value, length, 0, isolate).IsEmpty())
             return Vector<RefPtr<T> >();
 
         Vector<RefPtr<T> > result;
@@ -481,7 +481,7 @@ namespace WebCore {
         uint32_t length = 0;
         if (value->IsArray())
             length = v8::Local<v8::Array>::Cast(v8Value)->Length();
-        else if (toV8Sequence(value, length, isolate).IsEmpty())
+        else if (toV8Sequence(value, length, 0, isolate).IsEmpty())
             return Vector<T>();
 
         Vector<T> result;
@@ -510,7 +510,7 @@ namespace WebCore {
 
     // Validates that the passed object is a sequence type per WebIDL spec
     // http://www.w3.org/TR/2012/CR-WebIDL-20120419/#es-sequence
-    inline v8::Handle<v8::Value> toV8Sequence(v8::Handle<v8::Value> value, uint32_t& length, v8::Isolate* isolate)
+    inline v8::Handle<v8::Value> toV8Sequence(v8::Handle<v8::Value> value, uint32_t& length, bool* notASequence, v8::Isolate* isolate)
     {
         // Attempt converting to a sequence if the value is not already an array but is
         // any kind of object except for a native Date object or a native RegExp object.
@@ -518,7 +518,11 @@ namespace WebCore {
         // FIXME: Do we really need to special case Date and RegExp object?
         // https://www.w3.org/Bugs/Public/show_bug.cgi?id=22806
         if (!value->IsObject() || value->IsDate() || value->IsRegExp()) {
-            throwTypeError(isolate);
+            // Signal that the caller must handle the type error.
+            if (notASequence)
+                *notASequence = true;
+            else
+                throwTypeError(isolate);
             return v8Undefined();
         }
 
@@ -531,7 +535,11 @@ namespace WebCore {
         V8TRYCATCH(v8::Local<v8::Value>, lengthValue, object->Get(v8::String::NewSymbol("length")));
 
         if (lengthValue->IsUndefined() || lengthValue->IsNull()) {
-            throwTypeError(isolate);
+            // Signal that the caller must handle the type error.
+            if (notASequence)
+                *notASequence = true;
+            else
+                throwTypeError(isolate);
             return v8Undefined();
         }