Enable --verify-heap in release mode

src/flag-definitions.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 377 matching lines @@
 DEFINE_bool(collect_maps, true,
             "garbage collect maps from which no objects can be reached")
 DEFINE_bool(flush_code, true,
             "flush code that we expect not to use again before full gc")
 DEFINE_bool(incremental_marking, true, "use incremental marking")
 DEFINE_bool(incremental_marking_steps, true, "do incremental marking steps")
 DEFINE_bool(trace_incremental_marking, false,
             "trace progress of the incremental marking")
 DEFINE_bool(track_gc_object_stats, false,
             "track object counts and memory usage")
+#ifdef VERIFY_HEAP
+DEFINE_bool(verify_heap, false, "verify heap pointers before and after GC")
+#endif
 
 // v8.cc
 DEFINE_bool(use_idle_notification, true,
             "Use idle notification to reduce memory footprint.")
 // ic.cc
 DEFINE_bool(use_ic, true, "use inline caching")
 
 #ifdef LIVE_OBJECT_LIST
 // liveobjectlist.cc
 DEFINE_string(lol_workdir, NULL, "path for lol temp files")
@@ skipping 153 matching lines @@
 DEFINE_bool(print_scopes, false, "print scopes")
 
 // contexts.cc
 DEFINE_bool(trace_contexts, false, "trace contexts operations")
 
 // heap.cc
 DEFINE_bool(gc_greedy, false, "perform GC prior to some allocations")
 DEFINE_bool(gc_verbose, false, "print stuff during garbage collection")
 DEFINE_bool(heap_stats, false, "report heap statistics before and after GC")
 DEFINE_bool(code_stats, false, "report code statistics after GC")
-DEFINE_bool(verify_heap, false, "verify heap pointers before and after GC")
 DEFINE_bool(verify_native_context_separation, false,
             "verify that code holds on to at most one native context after GC")
 DEFINE_bool(print_handles, false, "report handles after GC")
 DEFINE_bool(print_global_handles, false, "report global handles after GC")
 
 // ic.cc
 DEFINE_bool(trace_ic, false, "trace inline cache state transitions")
 
 // interface.cc
 DEFINE_bool(print_interfaces, false, "print interfaces")
@@ skipping 117 matching lines @@
 #undef DEFINE_bool
 #undef DEFINE_int
 #undef DEFINE_string
 #undef DEFINE_implication
 
 #undef FLAG_MODE_DECLARE
 #undef FLAG_MODE_DEFINE
 #undef FLAG_MODE_DEFINE_DEFAULTS
 #undef FLAG_MODE_META
 #undef FLAG_MODE_DEFINE_IMPLICATIONS