Add expandable instances and lists to the vm service.

runtime/vm/object.h

Index: runtime/vm/object.h
diff --git a/runtime/vm/object.h b/runtime/vm/object.h
index 456fc5a455fadc993fd1c0fa699049299da1c6e2..881a4b4694279e2ad35a111043df66673e3ca3ba 100644
--- a/runtime/vm/object.h
+++ b/runtime/vm/object.h
@@ -2188,12 +2188,6 @@ class Field : public Object {
   static bool IsGetterName(const String& function_name);
   static bool IsSetterName(const String& function_name);
 
-  // When we print a field to a JSON stream, we want to make it appear
-  // that the value is a property of the field, so we allow the actual
-  // instance to be supplied here.
-  virtual void PrintToJSONStreamWithInstance(
-      JSONStream* stream, const Instance& instance, bool ref) const;
-
  private:
   friend class StoreInstanceFieldInstr;  // Generated code access to bit field.