Really remove io support when dart:io is unsupported.

runtime/bin/io_impl_sources.gypi

Index: runtime/bin/io_impl_sources.gypi
diff --git a/runtime/bin/io_impl_sources.gypi b/runtime/bin/io_impl_sources.gypi
index 8a9c7c5068177c5fb569f7b718d2e43415037272..af5c7129ca80afbf17d218ecd00b9e3b52eb0d19 100644
--- a/runtime/bin/io_impl_sources.gypi
+++ b/runtime/bin/io_impl_sources.gypi
@@ -14,6 +14,7 @@
     'eventhandler_linux.h',
     'eventhandler_macos.cc',
     'eventhandler_macos.h',
+    'eventhandler_unsupported.cc',
     'eventhandler_win.cc',
     'eventhandler_win.h',
     'file_system_watcher.cc',
@@ -21,6 +22,7 @@
     'file_system_watcher_android.cc',
     'file_system_watcher_linux.cc',
     'file_system_watcher_macos.cc',
+    'file_system_watcher_unsupported.cc',
     'file_system_watcher_win.cc',
     'filter.cc',
     'filter.h',
@@ -35,12 +37,14 @@
     'platform_android.cc',
     'platform_linux.cc',
     'platform_macos.cc',
+    'platform_unsupported.cc',
     'platform_win.cc',
     'process.cc',
     'process.h',
     'process_android.cc',
     'process_linux.cc',
     'process_macos.cc',
+    'process_unsupported.cc',
     'process_win.cc',
     '../../third_party/root_certificates/root_certificates.cc',
     'root_certificates_unsupported.cc',
@@ -58,6 +62,7 @@
     'socket_linux.h',
     'socket_macos.cc',
     'socket_macos.h',
+    'socket_unsupported.cc',
     'socket_win.cc',
     'socket_win.h',
     'stdio.cc',
@@ -65,30 +70,7 @@
     'stdio_android.cc',
     'stdio_linux.cc',
     'stdio_macos.cc',
+    'stdio_unsupported.cc',
     'stdio_win.cc',
   ],
-  'conditions': [
-    ['dart_io_support==1', {
-      'sources!' : [
-        'filter_unsupported.cc',
-        'io_service_unsupported.cc',
-      ],
-    },{  # else dart_io_support == 0
-      'sources!' : [
-        'filter.cc',
-        'filter.h',
-        'io_service.cc',
-        'io_service.h',
-        'io_service_no_ssl.cc',
-        'io_service_no_ssl.h',
-        '../../third_party/root_certificates/root_certificates.cc',
-        'root_certificates_unsupported.cc',
-        'secure_socket.h',
-        'secure_socket_boringssl.cc',
-        'secure_socket_boringssl.h',
-        'secure_socket_macos.cc',
-        'secure_socket_macos.h',
-      ],
-    }],
-  ],
 }