[wasm] Differentiate unnamed and empty names

src/isolate.cc

Index: src/isolate.cc
diff --git a/src/isolate.cc b/src/isolate.cc
index d04839ce5cf21bd2b3a8d1cc4e4ac90c04296131..66b469237b14bf5f5c8d1c902a92c6a18f91ce74 100644
--- a/src/isolate.cc
+++ b/src/isolate.cc
@@ -616,10 +616,11 @@ class CaptureStackTraceHelper {
         factory()->NewJSObject(isolate_->object_function());
 
     if (!function_key_.is_null()) {
-      Handle<Object> fun_name = handle(frame->function_name(), isolate_);
-      if (fun_name->IsUndefined())
-        fun_name = isolate_->factory()->InternalizeUtf8String(
-            Vector<const char>("<WASM>"));
+      String* fun_name_raw = frame->function_name();

[Yang, 2016/05/18 13:38:48]

Like noted previously, this having WasmFrame::function_name() just seems to add
a lot of code, and we are dealing with the case where we do have no name there
and here.

+      Handle<String> fun_name =
+          fun_name_raw == nullptr
+              ? isolate_->factory()->NewStringFromStaticChars("<WASM UNNAMED>")
+              : handle(fun_name_raw, isolate_);
       JSObject::AddProperty(stack_frame, function_key_, fun_name, NONE);
     }
     // Encode the function index as line number.