a === b -> identical(a, b)

runtime/bin/process_patch.dart

 // Copyright (c) 2012, 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.
 
 patch class Process {
   /* patch */ static Future<Process> start(String executable,
                                            List<String> arguments,
                                            [ProcessOptions options]) {
     _ProcessImpl process = new _ProcessImpl(executable, arguments, options);
     return process._start();
@@ skipping 34 matching lines @@
       var arg = arguments[i];
       if (arg is !String) {
         throw new ArgumentError("Non-string argument: $arg");
       }
       _arguments[i] = arguments[i];
       if (Platform.operatingSystem == 'windows') {
         _arguments[i] = _windowsArgumentEscape(_arguments[i]);
       }
     }
 
-    if (options !== null && options.workingDirectory !== null) {
+    if (options != null && options.workingDirectory != null) {
       _workingDirectory = options.workingDirectory;
       if (_workingDirectory is !String) {
         throw new ArgumentError(
             "WorkingDirectory is not a String: $_workingDirectory");
       }
     }
 
-    if (options !== null && options.environment !== null) {
+    if (options != null && options.environment != null) {
       var env = options.environment;
       if (env is !Map) {
         throw new ArgumentError("Environment is not a map: $env");
       }
       _environment = [];
       env.forEach((key, value) {
         if (key is !String || value is !String) {
           throw new ArgumentError(
               "Environment key or value is not a string: ($key, $value)");
         }
@@ skipping 109 matching lines @@
 
         int exitCode(List<int> ints) {
           var code = _intFromBytes(ints, 0);
           var negative = _intFromBytes(ints, 4);
           assert(negative == 0 || negative == 1);
           return (negative == 0) ? code : -code;
         }
 
         void handleExit() {
           _ended = true;
-          if (_onExit !== null) {
+          if (_onExit != null) {
             _onExit(exitCode(exitDataBuffer));
           }
           _out.close();
         }
 
         exitDataRead += _exitHandler.inputStream.readInto(
             exitDataBuffer, exitDataRead, EXIT_DATA_SIZE - exitDataRead);
         if (exitDataRead == EXIT_DATA_SIZE) {
           _exitHandler.close();
           handleExit();
@@ skipping 66 matching lines @@
 // _NonInteractiveProcess is used to implement the Process.run
 // method.
 class _NonInteractiveProcess {
   _NonInteractiveProcess(String path,
                          List<String> arguments,
                          ProcessOptions options) {
     _completer = new Completer<ProcessResult>();
     // Extract output encoding options and verify arguments.
     var stdoutEncoding = Encoding.UTF_8;
     var stderrEncoding = Encoding.UTF_8;
-    if (options !== null) {
-      if (options.stdoutEncoding !== null) {
+    if (options != null) {
+      if (options.stdoutEncoding != null) {
         stdoutEncoding = options.stdoutEncoding;
         if (stdoutEncoding is !Encoding) {
           throw new ArgumentError(
               'stdoutEncoding option is not an encoding: $stdoutEncoding');
         }
       }
-      if (options.stderrEncoding !== null) {
+      if (options.stderrEncoding != null) {
         stderrEncoding = options.stderrEncoding;
         if (stderrEncoding is !Encoding) {
           throw new ArgumentError(
               'stderrEncoding option is not an encoding: $stderrEncoding');
         }
       }
     }
 
     // Start the underlying process.
     var processFuture = new _ProcessImpl(path, arguments, options)._start();
@@ skipping 60 matching lines @@
 
 class _ProcessResult implements ProcessResult {
   const _ProcessResult(int this.exitCode,
                        String this.stdout,
                        String this.stderr);
 
   final int exitCode;
   final String stdout;
   final String stderr;
 }