[wasm] Differentiate unnamed and empty names

src/isolate.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/isolate.h"
 
 #include <stdlib.h>
 
 #include <fstream>  // NOLINT(readability/streams)
 #include <sstream>
@@ skipping 598 matching lines @@
                             NONE);
     }
     return stack_frame;
   }
 
   Handle<JSObject> NewStackFrameObject(WasmFrame* frame) {
     Handle<JSObject> stack_frame =
         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.
     if (!line_key_.is_null()) {
       JSObject::AddProperty(
           stack_frame, line_key_,
           isolate_->factory()->NewNumberFromInt(frame->function_index()), NONE);
     }
     // Encode the byte offset as column.
     if (!column_key_.is_null()) {
@@ skipping 2420 matching lines @@
   // Then check whether this scope intercepts.
   if ((flag & intercept_mask_)) {
     intercepted_flags_ |= flag;
     return true;
   }
   return false;
 }
 
 }  // namespace internal
 }  // namespace v8