Remove mirrors in product mode

runtime/vm/flag_list.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_FLAG_LIST_H_
 #define VM_FLAG_LIST_H_
 
 // List of all flags in the VM.
 // Flags can be one of three categories:
 // * P roduct flags: Can be set in any of the deployment modes, including in
 //   production.
 // * D ebug flags: Can only be set in debug VMs, which also have assertions
 //   enabled.
 // * R elease flags: Generally available flags except when building product.
 
 #define FLAG_LIST(P, R, D)                                                     \
 R(dedup_instructions, true, bool, false,                                       \
   "Canonicalize instructions when precompiling.")                              \
 R(disable_alloc_stubs_after_gc, false, bool, false,                            \
   "Stress testing flag.")                                                      \
 R(disassemble, false, bool, false,                                             \
   "Disassemble dart code.")                                                    \
 R(disassemble_optimized, false, bool, false,                                   \
   "Disassemble optimized code.")                                               \
 R(dump_symbol_stats, false, bool, false,                                       \
   "Dump symbol table statistics")                                              \
+R(enable_mirrors, false, bool, true,                                           \
+  "Disable to make importing dart:mirrors an error.")                          \
 R(gc_at_alloc, false, bool, false,                                             \
   "GC at every allocation.")                                                   \
 P(new_gen_ext_limit, int, 64,                                                  \
   "maximum total external size (MB) in new gen before triggering GC")          \
 R(pretenure_all, false, bool, false,                                           \
   "Global pretenuring (for testing).")                                         \
 P(pretenure_interval, int, 10,                                                 \
   "Back off pretenuring after this many cycles.")                              \
 P(pretenure_threshold, int, 98,                                                \
   "Trigger pretenuring when this many percent are promoted.")                  \
@@ skipping 23 matching lines @@
   "Enables verbose GC.")                                                       \
 P(verbose_gc_hdr, int, 40,                                                     \
   "Print verbose GC header interval.")                                         \
 R(verify_after_gc, false, bool, false,                                         \
   "Enables heap verification after GC.")                                       \
 R(verify_before_gc, false, bool, false,                                        \
   "Enables heap verification before GC.")                                      \
 
 
 #endif  // VM_FLAG_LIST_H_