Deserialize the scope chain for background parsing jobs on the main thread

src/background-parsing-task.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/background-parsing-task.h"
 #include "src/debug/debug.h"
 
 namespace v8 {
 namespace internal {
 
@@ skipping 24 matching lines @@
   // Parse eagerly with ignition since we will compile eagerly.
   info->set_allow_lazy_parsing(!(i::FLAG_ignition && i::FLAG_ignition_eager));
 
   if (options == ScriptCompiler::kProduceParserCache ||
       options == ScriptCompiler::kProduceCodeCache) {
     source_->info->set_cached_data(&script_data_);
   }
   // Parser needs to stay alive for finalizing the parsing on the main
   // thread.
   source_->parser.reset(new Parser(source_->info.get()));
+  source_->parser->DeserializeScopeChain(
+      source_->info.get(), Handle<Context>::null(),
+      Scope::DeserializationMode::kDeserializeOffHeap);
 }
 
 
 void BackgroundParsingTask::Run() {
   DisallowHeapAllocation no_allocation;
   DisallowHandleAllocation no_handles;
   DisallowHandleDereference no_deref;
 
   // Reset the stack limit of the parser to reflect correctly that we're on a
   // background thread.
   uintptr_t stack_limit =
       reinterpret_cast<uintptr_t>(&stack_limit) - stack_size_ * KB;
   source_->parser->set_stack_limit(stack_limit);
 
   // Nullify the Isolate temporarily so that the background parser doesn't
   // accidentally use it.
   Isolate* isolate = source_->info->isolate();
   source_->info->set_isolate(nullptr);
 
-  source_->parser->DeserializeScopeChain(
-      source_->info.get(), Handle<Context>::null(),
-      Scope::DeserializationMode::kDeserializeOffHeap);
   source_->parser->ParseOnBackground(source_->info.get());
 
   if (script_data_ != nullptr) {
     source_->cached_data.reset(new ScriptCompiler::CachedData(
         script_data_->data(), script_data_->length(),
         ScriptCompiler::CachedData::BufferOwned));
     script_data_->ReleaseDataOwnership();
     delete script_data_;
     script_data_ = nullptr;
   }
   source_->info->set_isolate(isolate);
 }
 }  // namespace internal
 }  // namespace v8