Remove --stop-at flag from several backends.

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 915 matching lines @@
 DEFINE_BOOL(enable_slow_asserts, false,
             "enable asserts that are slow to execute")
 #endif
 
 // codegen-ia32.cc / codegen-arm.cc / macro-assembler-*.cc
 DEFINE_BOOL(print_source, false, "pretty print source code")
 DEFINE_BOOL(print_builtin_source, false,
             "pretty print source code for builtins")
 DEFINE_BOOL(print_ast, false, "print source AST")
 DEFINE_BOOL(print_builtin_ast, false, "print source AST for builtins")
-DEFINE_STRING(stop_at, "", "function name where to insert a breakpoint")
 DEFINE_BOOL(trap_on_abort, false, "replace aborts by breakpoints")
 
 // compiler.cc
 DEFINE_BOOL(print_builtin_scopes, false, "print scopes for builtins")
 DEFINE_BOOL(print_scopes, false, "print scopes")
 
 // contexts.cc
 DEFINE_BOOL(trace_contexts, false, "trace contexts operations")
 
 // heap.cc
@@ skipping 204 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