Handle unicode correctly in CallPrinter

src/runtime/runtime-internal.cc

Index: src/runtime/runtime-internal.cc
diff --git a/src/runtime/runtime-internal.cc b/src/runtime/runtime-internal.cc
index a295190f0dc02a26690c6b6a880d49852108b5ee..3de0f16b1e63233ca72bdb4ab8fa311e3d9653b5 100644
--- a/src/runtime/runtime-internal.cc
+++ b/src/runtime/runtime-internal.cc
@@ -411,10 +411,8 @@ Handle<String> RenderCallSite(Isolate* isolate, Handle<Object> object) {
             : new ParseInfo(&zone, location.script()));
     if (Parser::ParseStatic(info.get())) {
       CallPrinter printer(isolate, location.function()->shared()->IsBuiltin());
-      const char* string = printer.Print(info->literal(), location.start_pos());
-      if (strlen(string) > 0) {
-        return isolate->factory()->NewStringFromAsciiChecked(string);
-      }
+      Handle<String> str = printer.Print(info->literal(), location.start_pos());
+      if (str->length() > 0) return str;
     } else {
       isolate->clear_pending_exception();
     }