Do not eagerly convert exception to string when creating a message object

src/messages.cc

Index: src/messages.cc
diff --git a/src/messages.cc b/src/messages.cc
index c21f96c0187a91370c44f0b948a27fbaf68b6da9..bd2792ec25f490a668e66678e658951d54d25e1c 100644
--- a/src/messages.cc
+++ b/src/messages.cc
@@ -280,22 +280,27 @@ Handle<String> MessageTemplate::FormatMessage(Isolate* isolate,
                                               int template_index,
                                               Handle<Object> arg) {
   Factory* factory = isolate->factory();
-  Handle<String> fmt_str = factory->InternalizeOneByteString(
-      STATIC_CHAR_VECTOR("$noSideEffectToString"));
-  Handle<JSFunction> fun = Handle<JSFunction>::cast(
-      Object::GetProperty(isolate->js_builtins_object(), fmt_str)
-          .ToHandleChecked());
-
-  MaybeHandle<Object> maybe_result =
-      Execution::TryCall(fun, isolate->js_builtins_object(), 1, &arg);
-  Handle<Object> result;
-  if (!maybe_result.ToHandle(&result) || !result->IsString()) {
-    return factory->InternalizeOneByteString(STATIC_CHAR_VECTOR("<error>"));
+  Handle<String> result_string;
+  if (arg->IsString()) {
+    result_string = Handle<String>::cast(arg);
+  } else {
+    Handle<String> fmt_str = factory->InternalizeOneByteString(
+        STATIC_CHAR_VECTOR("$noSideEffectToString"));
+    Handle<JSFunction> fun = Handle<JSFunction>::cast(
+        Object::GetProperty(isolate->js_builtins_object(), fmt_str)
+            .ToHandleChecked());
+
+    MaybeHandle<Object> maybe_result =
+        Execution::TryCall(fun, isolate->js_builtins_object(), 1, &arg);
+    Handle<Object> result;
+    if (!maybe_result.ToHandle(&result) || !result->IsString()) {
+      return factory->InternalizeOneByteString(STATIC_CHAR_VECTOR("<error>"));
+    }
+    result_string = Handle<String>::cast(result);
   }
   MaybeHandle<String> maybe_result_string = MessageTemplate::FormatMessage(
-      template_index, Handle<String>::cast(result), factory->empty_string(),
+      template_index, result_string, factory->empty_string(),
       factory->empty_string());
-  Handle<String> result_string;
   if (!maybe_result_string.ToHandle(&result_string)) {
     return factory->InternalizeOneByteString(STATIC_CHAR_VECTOR("<error>"));
   }