Reland of land: [Parse] ParseInfo owns the parsing Zone.

src/background-parsing-task.cc

Index: src/background-parsing-task.cc
diff --git a/src/background-parsing-task.cc b/src/background-parsing-task.cc
index e0af700ce5275871bc2ffb480b60ee4dc407b6e9..6b0e2efd0ddfc642d6814ab5f71813d9ccc67908 100644
--- a/src/background-parsing-task.cc
+++ b/src/background-parsing-task.cc
@@ -13,7 +13,6 @@
 void StreamedSource::Release() {
   parser.reset();
   info.reset();
-  zone.reset();
 }
 
 BackgroundParsingTask::BackgroundParsingTask(
@@ -29,10 +28,8 @@
 
   // Prepare the data for the internalization phase and compilation phase, which
   // will happen in the main thread after parsing.
-  Zone* zone = new Zone(isolate->allocator(), ZONE_NAME);
-  ParseInfo* info = new ParseInfo(zone);
+  ParseInfo* info = new ParseInfo(isolate->allocator());
   info->set_toplevel();
-  source->zone.reset(zone);
   source->info.reset(info);
   info->set_isolate(isolate);
   info->set_source_stream(source->source_stream.get());