Internalize the ast-value-factory before tracing in trace-parse. Otherwise the string-handle isn't …

src/parsing/parser.cc

Index: src/parsing/parser.cc
diff --git a/src/parsing/parser.cc b/src/parsing/parser.cc
index 36c17091193b55b791205100ac04933eab7d731b..1ef234f7ff2f5e79e646b27a685620ea88459561 100644
--- a/src/parsing/parser.cc
+++ b/src/parsing/parser.cc
@@ -884,6 +884,8 @@ FunctionLiteral* Parser::ParseLazy(Isolate* isolate, ParseInfo* info) {
 
   if (FLAG_trace_parse && result != NULL) {
     double ms = timer.Elapsed().InMillisecondsF();
+    // We need to make sure that the debug-name is available.
+    ast_value_factory()->Internalize(isolate);
     std::unique_ptr<char[]> name_chars = result->debug_name()->ToCString();
     PrintF("[parsing function: %s - took %0.3f ms]\n", name_chars.get(), ms);
   }