[turbofan] Remove native_context member from JSNativeContextSpecialization.

We don't need to store the native context explicitly anymore, the
broker already has it.

Bug: v8:7790
Change-Id: I1096953e3c56bed9d3a8d7d37b108888ef4ac7ec
Reviewed-on: https://chromium-review.googlesource.com/c/1270594
Commit-Queue: Georg Neis <neis@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56586}

src/compiler/js-native-context-specialization.cc

@@ -66,7 +66,6 @@ JSNativeContextSpecialization::JSNativeContextSpecialization(
       global_object_(native_context->global_object(), jsgraph->isolate()),
       global_proxy_(JSGlobalProxy::cast(native_context->global_proxy()),
                     jsgraph->isolate()),
-      native_context_(js_heap_broker, native_context),
       dependencies_(dependencies),
       zone_(zone),
       shared_zone_(shared_zone),

src/compiler/js-native-context-specialization.h

@@ -238,7 +238,9 @@ class V8_EXPORT_PRIVATE JSNativeContextSpecialization final
   Flags flags() const { return flags_; }
   Handle<JSGlobalObject> global_object() const { return global_object_; }
   Handle<JSGlobalProxy> global_proxy() const { return global_proxy_; }
-  const NativeContextRef& native_context() const { return native_context_; }
+  NativeContextRef native_context() const {
+    return js_heap_broker()->native_context();
+  }
   CompilationDependencies* dependencies() const { return dependencies_; }
   Zone* zone() const { return zone_; }
   Zone* shared_zone() const { return shared_zone_; }
@@ -248,7 +250,6 @@ class V8_EXPORT_PRIVATE JSNativeContextSpecialization final
   Flags const flags_;
   Handle<JSGlobalObject> global_object_;
   Handle<JSGlobalProxy> global_proxy_;
-  NativeContextRef native_context_;
   CompilationDependencies* const dependencies_;
   Zone* const zone_;
   Zone* const shared_zone_;

src/compiler/pipeline.cc

@@ -2012,6 +2012,8 @@ bool PipelineImpl::CreateGraph() {
     data->js_heap_broker()->StartSerializing();
     Run<SerializeStandardObjectsPhase>();
     Run<CopyMetadataForConcurrentCompilePhase>();
+  } else {
+    data->js_heap_broker()->SetNativeContextRef();
   }
 
   // Perform function context specialization and inlining (if enabled).
@@ -2048,7 +2050,6 @@ bool PipelineImpl::CreateGraph() {
       Run<CopyMetadataForConcurrentCompilePhase>();
       data->js_heap_broker()->StopSerializing();
     } else {
-      data->js_heap_broker()->SetNativeContextRef();
       // Type the graph and keep the Typer running such that new nodes get
       // automatically typed when they are created.
       Run<TyperPhase>(data->CreateTyper());