Reland [compiler] Enable shared function marking by default

src/flag-definitions.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This file defines all of the flags.  It is separated into different section,
 // for Debug, Release, Logging and Profiling, etc.  To add a new flag, find the
 // correct section, and use one of the DEFINE_ macros, without a trailing ';'.
 //
 // This include does not have a guard, because it is a template-style include,
 // which can be included multiple times in different modes.  It expects to have
@@ skipping 251 matching lines @@
 DEFINE_BOOL(track_double_fields, true, "track fields with double values")
 DEFINE_BOOL(track_heap_object_fields, true, "track fields with heap values")
 DEFINE_BOOL(track_computed_fields, true, "track computed boilerplate fields")
 DEFINE_IMPLICATION(track_double_fields, track_fields)
 DEFINE_IMPLICATION(track_heap_object_fields, track_fields)
 DEFINE_IMPLICATION(track_computed_fields, track_fields)
 DEFINE_BOOL(track_field_types, true, "track field types")
 DEFINE_IMPLICATION(track_field_types, track_fields)
 DEFINE_IMPLICATION(track_field_types, track_heap_object_fields)
 DEFINE_BOOL(smi_binop, true, "support smi representation in binary operations")
-DEFINE_BOOL(mark_shared_functions_for_tier_up, false,
+DEFINE_BOOL(mark_shared_functions_for_tier_up, true,
             "mark shared functions for tier up")
 
 // Flags for optimization types.
 DEFINE_BOOL(optimize_for_size, false,
             "Enables optimizations which favor memory size over execution "
             "speed")
 
 DEFINE_VALUE_IMPLICATION(optimize_for_size, max_semi_space_size, 1)
 
 // Flags for data representation optimizations
@@ skipping 933 matching lines @@
 #undef DEFINE_ALIAS_FLOAT
 #undef DEFINE_ALIAS_ARGS
 
 #undef FLAG_MODE_DECLARE
 #undef FLAG_MODE_DEFINE
 #undef FLAG_MODE_DEFINE_DEFAULTS
 #undef FLAG_MODE_META
 #undef FLAG_MODE_DEFINE_IMPLICATIONS
 
 #undef COMMA