Migrate flutter_tools to use package:platform (#7642)

packages/flutter_tools/lib/src/base/utils.dart

diff --git a/packages/flutter_tools/lib/src/base/utils.dart b/packages/flutter_tools/lib/src/base/utils.dart
index 1cdd05a..67518f3 100644
--- a/packages/flutter_tools/lib/src/base/utils.dart
+++ b/packages/flutter_tools/lib/src/base/utils.dart
@@ -10,15 +10,15 @@
 import 'package:path/path.dart' as path;
 
 import 'file_system.dart';
-import 'io.dart';
+import 'platform.dart';
 
 bool get isRunningOnBot {
   // https://docs.travis-ci.com/user/environment-variables/#Default-Environment-Variables
   // CHROME_HEADLESS is one property set on Flutter's Chrome Infra bots.
   return
-    Platform.environment['TRAVIS'] == 'true' ||
-    Platform.environment['CONTINUOUS_INTEGRATION'] == 'true' ||
-    Platform.environment['CHROME_HEADLESS'] == '1';
+    platform.environment['TRAVIS'] == 'true' ||
+    platform.environment['CONTINUOUS_INTEGRATION'] == 'true' ||
+    platform.environment['CHROME_HEADLESS'] == '1';
 }
 
 String hex(List<int> bytes) {