Use displayName in Error.stack rendering if present.

src/messages.cc

 // Copyright 2011 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/messages.h"
 
 #include "src/api.h"
 #include "src/execution.h"
 #include "src/isolate-inl.h"
 #include "src/string-builder.h"
@@ skipping 173 matching lines @@
 
   Handle<Object> script(fun_->shared()->script(), isolate_);
   if (script->IsScript() &&
       Handle<Script>::cast(script)->compilation_type() ==
           Script::COMPILATION_TYPE_EVAL) {
     return isolate_->factory()->eval_string();
   }
   return isolate_->factory()->null_value();
 }
 
+Handle<Object> CallSite::GetDebugName() {
+  Handle<Object> name = JSReceiver::GetDataProperty(
+      fun_, isolate_->factory()->display_name_string());
+  if (name->IsString() && String::cast(*name)->length() != 0) {
+    return Handle<String>::cast(name);
+  }
+  return isolate_->factory()->null_value();
+}
 
 Handle<Object> CallSite::GetScriptNameOrSourceUrl() {
   Handle<Object> script_obj(fun_->shared()->script(), isolate_);
   if (script_obj->IsScript()) {
     Handle<Script> script = Handle<Script>::cast(script_obj);
     Object* source_url = script->source_url();
     if (source_url->IsString()) return Handle<Object>(source_url, isolate_);
     return Handle<Object>(script->name(), isolate_);
   }
   return isolate_->factory()->null_value();
@@ skipping 196 matching lines @@
       builder.AppendCharacter(*c);
     }
   }
 
   return builder.Finish();
 }
 
 
 }  // namespace internal
 }  // namespace v8