Add support for killing a process with a given PID to dart:io

sdk/lib/_internal/compiler/js_lib/io_patch.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import 'dart:_js_helper' show patch;
 
 @patch
 class _Directory {
   @patch
   static _current() {
@@ skipping 287 matching lines @@
       String executable,
       List<String> arguments,
       {String workingDirectory,
        Map<String, String> environment,
        bool includeParentEnvironment: true,
        bool runInShell: false,
        Encoding stdoutEncoding: SYSTEM_ENCODING,
        Encoding stderrEncoding: SYSTEM_ENCODING}) {
     throw new UnsupportedError("Process.runSync");
   }
+
+  @patch
+  static bool killPid(
+      int pid, [ProcessSignal signal = ProcessSignal.SIGTERM]) {
+    throw new UnsupportedError("Process.killPid");
+  }
 }
 
 @patch
 class InternetAddress {
   @patch
   static InternetAddress get LOOPBACK_IP_V4 {
     throw new UnsupportedError("InternetAddress.LOOPBACK_IP_V4");
   }
   @patch
   static InternetAddress get LOOPBACK_IP_V6 {
@@ skipping 204 matching lines @@
   }
 }
 
 @patch
 class _IOService {
   @patch
   static Future _dispatch(int request, List data) {
     throw new UnsupportedError("_IOService._dispatch");
   }
 }