[parser] Skipping inner funcs: allow handle deref when restoring the data.

This stopped working because of r47337 (
https://chromium-review.googlesource.com/c/v8/v8/+/605949/8/src/compiler.cc#418
).

Also enhanced the test so that it would've caught this.

BUG=v8:5516

Change-Id: I933a8b5d787c3eb8b2cc230e2b35df1f25b500e7
Reviewed-on: https://chromium-review.googlesource.com/625618Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47498}

src/ast/scopes.cc

@@ -665,6 +665,7 @@ void DeclarationScope::Analyze(ParseInfo* info) {
   if (scope->must_use_preparsed_scope_data_) {
     DCHECK(FLAG_preparser_scope_analysis);
     DCHECK_EQ(scope->scope_type_, ScopeType::FUNCTION_SCOPE);
+    allow_deref.emplace();
     info->consumed_preparsed_scope_data()->RestoreScopeAllocationData(scope);
   }
 

src/compiler.cc

@@ -407,6 +407,9 @@ std::unique_ptr<CompilationJob> GenerateUnoptimizedCode(
   DisallowHandleDereference no_deref;
   DCHECK(inner_function_jobs->empty());
 
+  DCHECK_IMPLIES(parse_info->consumed_preparsed_scope_data()->HasData(),
+                 ThreadId::Current().Equals(isolate->thread_id()));
+
   Compiler::EagerInnerFunctionLiterals inner_literals;
   if (!Compiler::Analyze(parse_info, &inner_literals)) {
     return std::unique_ptr<CompilationJob>();

test/mjsunit/skipping-inner-functions.js

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --preparser-scope-analysis
+// Flags: --preparser-scope-analysis --enable-slow-asserts
 
 (function TestBasicSkipping() {
   var result = 0;
@@ -82,7 +82,7 @@
 })();
 
 // Skippable top level functions.
-let result = 0;
+var result = 0;
 function lazy_top_level(ctxt_alloc_param) {
   let ctxt_alloc_var = 24;
   function skip_me() {