Revert r43217, r43215, r43208, r43207, and r43202.

runtime/vm/isolate.h

Index: runtime/vm/isolate.h
diff --git a/runtime/vm/isolate.h b/runtime/vm/isolate.h
index 999a437d85d3c558215e8c7d3cee2b0a3ec1fdce..3019f479da0a48c6f0b8cc2e0bb8b45b0e20ca16 100644
--- a/runtime/vm/isolate.h
+++ b/runtime/vm/isolate.h
@@ -408,6 +408,13 @@ class Isolate : public BaseIsolate {
     return create_callback_;
   }
 
+  static void SetServiceCreateCallback(Dart_ServiceIsolateCreateCalback cb) {
+    service_create_callback_ = cb;
+  }
+  static Dart_ServiceIsolateCreateCalback ServiceCreateCallback() {
+    return service_create_callback_;
+  }
+
   static void SetInterruptCallback(Dart_IsolateInterruptCallback cb) {
     interrupt_callback_ = cb;
   }
@@ -731,6 +738,7 @@ class Isolate : public BaseIsolate {
   static Dart_FileCloseCallback file_close_callback_;
   static Dart_EntropySource entropy_source_callback_;
   static Dart_IsolateInterruptCallback vmstats_callback_;
+  static Dart_ServiceIsolateCreateCalback service_create_callback_;
 
   // Manage list of existing isolates.
   static void AddIsolateTolist(Isolate* isolate);