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

src/parsing/parser.cc

Index: src/parsing/parser.cc
diff --git a/src/parsing/parser.cc b/src/parsing/parser.cc
index f54bae4cc9807f9f599c44c1534e2d825e2cd1ae..b0b8cda42cb02db4537cf399b6c4b5162c1a32bc 100644
--- a/src/parsing/parser.cc
+++ b/src/parsing/parser.cc
@@ -771,6 +771,7 @@ Parser::Parser(ParseInfo* info)
 void Parser::DeserializeScopeChain(
     ParseInfo* info, Handle<Context> context,
     Scope::DeserializationMode deserialization_mode) {
+  DCHECK(ThreadId::Current().Equals(info->isolate()->thread_id()));
   // TODO(wingo): Add an outer SCRIPT_SCOPE corresponding to the native
   // context, which will have the "this" binding for script scopes.
   DeclarationScope* script_scope = NewScriptScope();