Remove unneeded variable usage analysis.

src/flag-definitions.h

 // Copyright 2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 213 matching lines @@
 // simulator-arm.cc and simulator-mips.cc
 DEFINE_bool(trace_sim, false, "trace simulator execution")
 DEFINE_int(stop_sim_at, 0, "Simulator stop after x number of instructions")
 
 // top.cc
 DEFINE_bool(trace_exception, false,
             "print stack trace when throwing exceptions")
 DEFINE_bool(preallocate_message_memory, false,
             "preallocate some memory to build stack traces.")
 
-// usage-analyzer.cc
-DEFINE_bool(usage_computation, true, "compute variable usage counts")
-
 // v8.cc
 DEFINE_bool(preemption, false,
             "activate a 100ms timer that switches between V8 threads")
 
 // Regexp
 DEFINE_bool(trace_regexps, false, "trace regexp execution")
 DEFINE_bool(regexp_optimization, true, "generate optimized regexp code")
 DEFINE_bool(regexp_entry_native, true, "use native code to enter regexp")
 
 // Testing flags test/cctest/test-{flags,api,serialization}.cc
@@ skipping 178 matching lines @@
 #undef FLAG
 
 #undef DEFINE_bool
 #undef DEFINE_int
 #undef DEFINE_string
 
 #undef FLAG_MODE_DECLARE
 #undef FLAG_MODE_DEFINE
 #undef FLAG_MODE_DEFINE_DEFAULTS
 #undef FLAG_MODE_META