Reland "Recognize and optimize a.runtimeType == b.runtimeType pattern."

runtime/vm/isolate.h

Index: runtime/vm/isolate.h
diff --git a/runtime/vm/isolate.h b/runtime/vm/isolate.h
index f29f6666330b84b27306ff2ec38695791592b12a..62da15aed8d099e188f96c08fc24daf40c343aae 100644
--- a/runtime/vm/isolate.h
+++ b/runtime/vm/isolate.h
@@ -224,6 +224,9 @@ class Isolate : public BaseIsolate {
 
   ObjectStore* object_store() const { return object_store_; }
   void set_object_store(ObjectStore* value) { object_store_ = value; }
+  static intptr_t object_store_offset() {
+    return OFFSET_OF(Isolate, object_store_);
+  }
 
   ApiState* api_state() const { return api_state_; }
   void set_api_state(ApiState* value) { api_state_ = value; }
@@ -733,6 +736,7 @@ class Isolate : public BaseIsolate {
   RawUserTag* current_tag_;
   RawUserTag* default_tag_;
   RawCode* ic_miss_code_;
+  ObjectStore* object_store_;
   ClassTable class_table_;
   bool single_step_;
   bool skip_step_;  // skip the next single step.
@@ -748,7 +752,6 @@ class Isolate : public BaseIsolate {
   uint64_t pause_capability_;
   uint64_t terminate_capability_;
   bool errors_fatal_;
-  ObjectStore* object_store_;
   uword top_exit_frame_info_;
   void* init_callback_data_;
   Dart_EnvironmentCallback environment_callback_;