Replace linked list of loaded libraries

runtime/vm/raw_object.h

Index: runtime/vm/raw_object.h
===================================================================
--- runtime/vm/raw_object.h	(revision 7922)
+++ runtime/vm/raw_object.h	(working copy)
@@ -668,10 +668,9 @@
   RawArray* imports_;            // List of libraries imported without prefix.
   RawArray* imported_into_;      // List of libraries where this library
                                  // is imported into without a prefix.
-  RawLibrary* next_registered_;  // Linked list of registered libraries.
   RawArray* loaded_scripts_;     // Array of scripts loaded in this library.
   RawObject** to() {
-    return reinterpret_cast<RawObject**>(&ptr()->next_registered_);
+    return reinterpret_cast<RawObject**>(&ptr()->loaded_scripts_);
   }
 
   intptr_t num_imports_;         // Number of entries in imports_.