Eliminate imported_into pointers in Library

runtime/vm/raw_object.h

Index: runtime/vm/raw_object.h
===================================================================
--- runtime/vm/raw_object.h	(revision 10983)
+++ runtime/vm/raw_object.h	(working copy)
@@ -710,7 +710,6 @@
   RawArray* dictionary_;         // Top-level names in this library.
   RawArray* anonymous_classes_;  // Classes containing top-level elements.
   RawArray* imports_;            // List of libraries imported without prefix.
-  RawArray* imported_into_;      // List of libraries where this library
                                  // is imported into without a prefix.
   RawArray* loaded_scripts_;     // Array of scripts loaded in this library.
   RawObject** to() {
@@ -719,7 +718,6 @@
 
   intptr_t index_;               // Library id number.
   intptr_t num_imports_;         // Number of entries in imports_.
-  intptr_t num_imported_into_;   // Number of entries in imported_into_.
   intptr_t num_anonymous_;       // Number of entries in anonymous_classes_.
   Dart_NativeEntryResolver native_entry_resolver_;  // Resolves natives.
   bool corelib_imported_;