[debugger] debug-evaluate should not not modify local values.

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 534 matching lines @@
               "expose gc extension under the specified name")
 DEFINE_IMPLICATION(expose_gc_as, expose_gc)
 DEFINE_BOOL(expose_externalize_string, false,
             "expose externalize string extension")
 DEFINE_BOOL(expose_trigger_failure, false, "expose trigger-failure extension")
 DEFINE_INT(stack_trace_limit, 10, "number of stack frames to capture")
 DEFINE_BOOL(builtins_in_stack_traces, false,
             "show built-in functions in stack traces")
 DEFINE_BOOL(disable_native_files, false, "disable builtin natives files")
 
+// debugger
+DEFINE_BOOL(debug_eval_readonly_locals, true,

[Michael Starzinger, 2015/12/14 12:11:23]

nit/suggestion: There already is a section for "debug.cc" a couple of lines
further down, would it make sense to move this flag down? WDYT?

+            "do not update locals after debug-evaluate")
+
 // builtins-ia32.cc
 DEFINE_BOOL(inline_new, true, "use fast inline allocation")
 
 // codegen-ia32.cc / codegen-arm.cc
 DEFINE_BOOL(trace_codegen, false,
             "print name of functions for which code is generated")
 DEFINE_BOOL(trace, false, "trace function calls")
 DEFINE_BOOL(mask_constants_with_cookie, true,
             "use random jit cookie to mask large constants")
 
@@ skipping 559 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