[d8] Remove "os" object from d8.

src/d8.gyp

Index: src/d8.gyp
diff --git a/src/d8.gyp b/src/d8.gyp
index 2e4a6e0cc5cf7edc8804ccabaebedc13944b5f41..7010318d8a801cf0b3d0acad7f1d3845c7426d0b 100644
--- a/src/d8.gyp
+++ b/src/d8.gyp
@@ -54,14 +54,6 @@
         [ 'want_separate_host_toolset==1', {
           'toolsets': [ '<(v8_toolset_for_d8)', ],
         }],
-        ['(OS=="linux" or OS=="mac" or OS=="freebsd" or OS=="netbsd" \
-           or OS=="openbsd" or OS=="solaris" or OS=="android" \
-           or OS=="qnx" or OS=="aix")', {
-             'sources': [ 'd8-posix.cc', ]
-           }],
-        [ 'OS=="win"', {
-          'sources': [ 'd8-windows.cc', ]
-        }],
         [ 'component!="shared_library"', {
           'sources': [
             '<(SHARED_INTERMEDIATE_DIR)/d8-js.cc',