Enable --thin-strings with --turbo.

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 240 matching lines @@
 HARMONY_SHIPPING(FLAG_SHIPPING_FEATURES)
 #undef FLAG_SHIPPING_FEATURES
 
 DEFINE_BOOL(future, false,
             "Implies all staged features that we want to ship in the "
             "not-too-far future")
 DEFINE_IMPLICATION(future, turbo)
 
 DEFINE_IMPLICATION(turbo, ignition_staging)
 DEFINE_IMPLICATION(turbo, enable_fast_array_builtins)
+DEFINE_IMPLICATION(turbo, thin_strings)
 
 // TODO(rmcilroy): Remove ignition-staging and set these implications directly
 // with the turbo flag.
 DEFINE_BOOL(ignition_staging, false, "use ignition with all staged features")
 DEFINE_IMPLICATION(ignition_staging, ignition)
 DEFINE_IMPLICATION(ignition_staging, compiler_dispatcher)
 DEFINE_IMPLICATION(ignition_staging, validate_asm)
 
 // Flags for experimental implementation features.
 DEFINE_BOOL(allocation_site_pretenuring, true,
@@ skipping 1037 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