[parser] Ensure the isolate is not null in UpdateStatistics

A stricter V8-side check to flush out the linked bug.

Bug: v8:10460
Change-Id: I20a0026e35719632e90f0a00bc49eb27d81b273b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2335061
Auto-Submit: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69197}

src/parsing/parser.cc

@@ -3096,6 +3096,8 @@ template void Parser::HandleSourceURLComments(OffThreadIsolate* isolate,
                                               Handle<Script> script);
 
 void Parser::UpdateStatistics(Isolate* isolate, Handle<Script> script) {
+  CHECK_NOT_NULL(isolate);
+
   // Move statistics to Isolate.
   for (int feature = 0; feature < v8::Isolate::kUseCounterFeatureCount;
        ++feature) {