[diagnostics] Fix printing empty ScopeInfos

(See bug for repro.)

Bug: v8:11571
Change-Id: I7cf7ddad1c031c476d29edf5a3922c64079c186b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2764462Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/master@{#73441}

src/diagnostics/objects-printer.cc

@@ -2302,8 +2302,8 @@ void PrintScopeInfoList(ScopeInfo scope_info, std::ostream& os,
 
 void ScopeInfo::ScopeInfoPrint(std::ostream& os) {  // NOLINT
   PrintHeader(os, "ScopeInfo");
-  if (length() == 0) {
-    os << "\n - length = 0\n";
+  if (IsEmpty()) {
+    os << "\n - empty\n";
     return;
   }
   int flags = Flags();