Use a fixed random seed per default.

tools/gyp/v8.gyp

 # Copyright 2012 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 10 matching lines @@
 # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 {
   'variables': {
     'v8_code': 1,
+    'v8_random_seed%': 314159265,
   },
   'includes': ['../../build/toolchain.gypi', '../../build/features.gypi'],
   'targets': [
     {
       'target_name': 'v8',
       'dependencies_traverse': 1,
       'conditions': [
         ['want_separate_host_toolset==1', {
           'toolsets': ['host', 'target'],
         }, {
@@ skipping 108 matching lines @@
             '<(PRODUCT_DIR)/<(EXECUTABLE_PREFIX)mksnapshot.<(v8_target_arch)<(EXECUTABLE_SUFFIX)',
           ],
           'outputs': [
             '<(INTERMEDIATE_DIR)/snapshot.cc',
           ],
           'variables': {
             'mksnapshot_flags': [
               '--log-snapshot-positions',
               '--logfile', '<(INTERMEDIATE_DIR)/snapshot.log',
             ],
+            'conditions': [
+              ['v8_random_seed!=0', {
+                'mksnapshot_flags': ['--random-seed', '<(v8_random_seed)'],
+              }],
+            ],
           },
           'action': [
             '<@(_inputs)',
             '<@(mksnapshot_flags)',
             '<@(_outputs)'
           ],
         },
       ],
     },
     {
@@ skipping 886 matching lines @@
         }],
         ['v8_compress_startup_data=="bz2"', {
           'libraries': [
             '-lbz2',
           ]
         }],
       ],
     },
   ],
 }