Clean up IOService implementation to be shared between patched and non-patched code.

runtime/bin/socket_patch.dart

Index: runtime/bin/socket_patch.dart
diff --git a/runtime/bin/socket_patch.dart b/runtime/bin/socket_patch.dart
index bc2aacc92ad3b858f5c70cbbd214710084defc7f..0042aed1eb3a977afcdc850596ecb3721fe50748 100644
--- a/runtime/bin/socket_patch.dart
+++ b/runtime/bin/socket_patch.dart
@@ -222,7 +222,7 @@ class _NativeSocket extends NativeFieldWrapperClass1 {
 
   static Future<List<InternetAddress>> lookup(
       String host, {InternetAddressType type: InternetAddressType.ANY}) {
-    return IOService.dispatch(SOCKET_LOOKUP, [host, type._value])
+    return _IOService.dispatch(_SOCKET_LOOKUP, [host, type._value])
         .then((response) {
           if (isErrorResponse(response)) {
             throw createError(response, "Failed host lookup: '$host'");
@@ -236,7 +236,7 @@ class _NativeSocket extends NativeFieldWrapperClass1 {
   }
 
   static Future<InternetAddress> reverseLookup(InternetAddress addr) {
-    return IOService.dispatch(SOCKET_REVERSE_LOOKUP, [addr._sockaddr_storage])
+    return _IOService.dispatch(_SOCKET_REVERSE_LOOKUP, [addr._sockaddr_storage])
         .then((response) {
           if (isErrorResponse(response)) {
             throw createError(response, "Failed reverse host lookup", addr);
@@ -250,7 +250,7 @@ class _NativeSocket extends NativeFieldWrapperClass1 {
       bool includeLoopback: false,
       bool includeLinkLocal: false,
       InternetAddressType type: InternetAddressType.ANY}) {
-    return IOService.dispatch(SOCKET_LIST_INTERFACES, [type._value])
+    return _IOService.dispatch(_SOCKET_LIST_INTERFACES, [type._value])
         .then((response) {
           if (isErrorResponse(response)) {
             throw createError(response, "Failed listing interfaces");