[turbofan] Add single --turbo flag.

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 362 matching lines @@
 DEFINE_BOOL(block_concurrent_recompilation, false,
             "block queued jobs until released")
 DEFINE_BOOL(concurrent_osr, true, "concurrent on-stack replacement")
 DEFINE_IMPLICATION(concurrent_osr, concurrent_recompilation)
 
 DEFINE_BOOL(omit_map_checks_for_leaf_maps, true,
             "do not emit check maps for constant values that have a leaf map, "
             "deoptimize the optimized code if the layout of the maps changes.")
 
 // Flags for TurboFan.
+DEFINE_BOOL(turbo, false, "enable TurboFan compiler")
+DEFINE_IMPLICATION(turbo, turbo_deoptimization)
 DEFINE_STRING(turbo_filter, "~", "optimization filter for TurboFan compiler")
 DEFINE_BOOL(trace_turbo, false, "trace generated TurboFan IR")
 DEFINE_BOOL(trace_turbo_graph, false, "trace generated TurboFan graphs")
 DEFINE_IMPLICATION(trace_turbo_graph, trace_turbo)
 DEFINE_STRING(trace_turbo_cfg_file, NULL,
               "trace turbo cfg graph (for C1 visualizer) to a given file name")
 DEFINE_BOOL(trace_turbo_types, true, "trace TurboFan's types")
 DEFINE_BOOL(trace_turbo_scheduler, false, "trace TurboFan's scheduler")
 DEFINE_BOOL(trace_turbo_reduction, false, "trace TurboFan's various reducers")
 DEFINE_BOOL(trace_turbo_jt, false, "trace TurboFan's jump threading")
@@ skipping 652 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