Let's try this again. This time actually include the new platform...

build/temp_gyp/v8.gyp

 # Copyright (c) 2009 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # TODO(mark): Upstream this file to v8.
 {
   'variables': {
     'chromium_code': 1,
     'base_source_files': [
       '../../v8/src/third_party/dtoa/dtoa.c',
@@ skipping 46 matching lines @@
       '../../v8/src/conversions-inl.h',
       '../../v8/src/conversions.cc',
       '../../v8/src/conversions.h',
       '../../v8/src/counters.cc',
       '../../v8/src/counters.h',
       '../../v8/src/cpu-arm.cc',
       '../../v8/src/cpu-ia32.cc',
       '../../v8/src/cpu.h',
       '../../v8/src/dateparser.cc',
       '../../v8/src/dateparser.h',
+      '../../v8/src/dateparser-inl.h',
       '../../v8/src/debug-arm.cc',
       '../../v8/src/debug-ia32.cc',
       '../../v8/src/debug.cc',
       '../../v8/src/debug.h',
       '../../v8/src/debug-agent.cc',
       '../../v8/src/debug-agent.h',
       '../../v8/src/disasm-arm.cc',
       '../../v8/src/disasm-ia32.cc',
       '../../v8/src/disasm.h',
       '../../v8/src/disassembler.cc',
@@ skipping 79 matching lines @@
       '../../v8/src/regexp-macro-assembler-irregexp-inl.h',
       '../../v8/src/regexp-macro-assembler-irregexp.cc',
       '../../v8/src/regexp-macro-assembler-irregexp.h',
       '../../v8/src/regexp-macro-assembler-tracer.cc',
       '../../v8/src/regexp-macro-assembler-tracer.h',
       '../../v8/src/regexp-macro-assembler.cc',
       '../../v8/src/regexp-macro-assembler.h',
       '../../v8/src/regexp-stack.cc',
       '../../v8/src/regexp-stack.h',
       '../../v8/src/register-allocator.h',
+      '../../v8/src/register-allocator-inl.h',
       '../../v8/src/register-allocator.cc',
       '../../v8/src/register-allocator-arm.cc',
       '../../v8/src/register-allocator-ia32.cc',
       '../../v8/src/rewriter.cc',
       '../../v8/src/rewriter.h',
       '../../v8/src/runtime.cc',
       '../../v8/src/runtime.h',
       '../../v8/src/scanner.cc',
       '../../v8/src/scanner.h',
       '../../v8/src/scopeinfo.cc',
@@ skipping 150 matching lines @@
         '<@(base_source_files)',
       ],
       'sources!': [
         '<@(not_base_source_files)',
       ],
       'sources/': [
         ['exclude', '-arm\\.cc$'],
         ['exclude', 'src/platform-.*\\.cc$' ],
       ],
       'conditions': [
-        ['OS=="linux"', {'sources/': [['include', 'src/platform-linux\\.cc$']]}],
-        ['OS=="mac"', {'sources/': [['include', 'src/platform-macos\\.cc$']]}],
+        ['OS=="linux"', {'sources/': [['include', 'src/platform-linux\\.cc$', 'src/platform-posix\\.cc$']]}],
+        ['OS=="mac"', {'sources/': [['include', 'src/platform-macos\\.cc$', 'src/platform-posix\\.cc$']]}],
         ['OS=="win"', {
           'sources/': [['include', 'src/platform-win32\\.cc$']],
           # 4355, 4800 came from common.vsprops
           # 4018, 4244 were a per file config on dtoa-config.c
           # TODO: It's probably possible and desirable to stop disabling the
           # dtoa-specific warnings by modifying dtoa as was done in Chromium
           # r9255.  Refer to that revision for details.
           'msvs_disabled_warnings': [4355, 4800, 4018, 4244],
           'link_settings':  {
             'libraries': [ '-lwinmm.lib' ],
@@ skipping 203 matching lines @@
           ]},
         }],
         [ 'OS=="win"', {
           'sources!': [ '../../v8/src/d8-readline.cc' ],
         }],
       ],
     },
   ]}], # OS != "linux" (temporary, TODO(sgk))
   ],
 }