Backport hash collision workaround to 3.6.

src/flag-definitions.h

 // Copyright 2011 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 301 matching lines @@
 DEFINE_bool(check_icache, false, "Check icache flushes in ARM simulator")
 DEFINE_int(stop_sim_at, 0, "Simulator stop after x number of instructions")
 DEFINE_int(sim_stack_alignment, 8,
            "Stack alingment in bytes in simulator (4 or 8, 8 is default)")
 
 // isolate.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.")
+DEFINE_bool(randomize_string_hashes,
+            true,
+            "randomize string hashes to avoid predictable hash collisions "
+            "(with snapshots this option cannot override the baked-in seed)")
+DEFINE_int(string_hash_seed,
+           0,
+           "Fixed seed to use to string hashing (0 means random)"
+           "(with snapshots this option cannot override the baked-in seed)")
 
 // v8.cc
 DEFINE_bool(preemption, false,
             "activate a 100ms timer that switches between V8 threads")
 
 // Regexp
 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 186 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