Use signaling NaN for holes in fixed double arrays.

build/toolchain.gypi

 # Copyright 2013 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 205 matching lines @@
                   [ 'arm_thumb==1', {
                     'cflags': ['-mthumb',],
                   }],
                   [ 'arm_thumb==0', {
                     'cflags': ['-marm',],
                   }],
                 ],
               }, {
                 # 'v8_target_arch!=target_arch'
                 # Target not built with an Arm CXX compiler (simulator build).
+                'cflags': [
+                  '-msse2',
+                  '-mfpmath=sse',
+                  '-mmmx',  # Allows mmintrin.h for MMX intrinsics.
+                ],
                 'conditions': [
                   [ 'arm_float_abi=="hard"', {
                     'defines': [
                       'USE_EABI_HARDFLOAT=1',
                     ],
                   }],
                   [ 'arm_float_abi=="softfp" or arm_float_abi=="default"', {
                     'defines': [
                       'USE_EABI_HARDFLOAT=0',
                     ],
@@ skipping 568 matching lines @@
       }],
       ['OS=="win" and v8_enable_prof==1', {
         'msvs_settings': {
           'VCLinkerTool': {
             'GenerateMapFile': 'true',
           },
         },
       }],
       ['(OS=="linux" or OS=="freebsd" or OS=="openbsd" or OS=="solaris" \
          or OS=="netbsd" or OS=="mac" or OS=="android" or OS=="qnx") and \
+        (v8_target_arch=="ia32")', {
+        'cflags': [
+          '-msse2',
+          '-mfpmath=sse',
+          '-mmmx',  # Allows mmintrin.h for MMX intrinsics.
+        ],
+      }],
+      ['(OS=="linux" or OS=="freebsd" or OS=="openbsd" or OS=="solaris" \
+         or OS=="netbsd" or OS=="mac" or OS=="android" or OS=="qnx") and \
         (v8_target_arch=="arm" or v8_target_arch=="ia32" or \
          v8_target_arch=="x87" or v8_target_arch=="mips" or \
          v8_target_arch=="mipsel" or v8_target_arch=="ppc")', {
         'target_conditions': [
           ['_toolset=="host"', {
             'conditions': [
               ['host_cxx_is_biarch==1', {
                 'cflags': [ '-m32' ],
                 'ldflags': [ '-m32' ]
               }],
@@ skipping 299 matching lines @@
           ['v8_enable_slow_dchecks==1', {
             'defines': [
               'ENABLE_SLOW_DCHECKS',
             ],
           }],
         ],  # conditions
       },  # Release
     },  # configurations
   },  # target_defaults
 }