Declare locals final where not reassigned (flutter_tools) (#8570)

packages/flutter_tools/lib/src/version.dart

diff --git a/packages/flutter_tools/lib/src/version.dart b/packages/flutter_tools/lib/src/version.dart
index 3bdd2e7..cf8230d 100644
--- a/packages/flutter_tools/lib/src/version.dart
+++ b/packages/flutter_tools/lib/src/version.dart
@@ -19,9 +19,9 @@
   FlutterVersion(this.flutterRoot) {
     _channel = _runGit('git rev-parse --abbrev-ref --symbolic @{u}');
 
-    int slash = _channel.indexOf('/');
+    final int slash = _channel.indexOf('/');
     if (slash != -1) {
-      String remote = _channel.substring(0, slash);
+      final String remote = _channel.substring(0, slash);
       _repositoryUrl = _runGit('git ls-remote --get-url $remote');
       _channel = _channel.substring(slash + 1);
     } else if (_channel.isEmpty) {
@@ -59,10 +59,10 @@
 
   @override
   String toString() {
-    String flutterText = 'Flutter • channel $channel • ${repositoryUrl == null ? 'unknown source' : repositoryUrl}';
-    String frameworkText = 'Framework • revision $frameworkRevisionShort ($frameworkAge) • $frameworkCommitDate';
-    String engineText = 'Engine • revision $engineRevisionShort';
-    String toolsText = 'Tools • Dart $dartSdkVersion';
+    final String flutterText = 'Flutter • channel $channel • ${repositoryUrl == null ? 'unknown source' : repositoryUrl}';
+    final String frameworkText = 'Framework • revision $frameworkRevisionShort ($frameworkAge) • $frameworkCommitDate';
+    final String engineText = 'Engine • revision $engineRevisionShort';
+    final String toolsText = 'Tools • Dart $dartSdkVersion';
 
     // Flutter • channel master • https://github.com/flutter/flutter.git
     // Framework • revision 2259c59be8 • 19 minutes ago • 2016-08-15 22:51:40
@@ -102,7 +102,7 @@
 }
 
 String _runSync(List<String> command, String cwd) {
-  ProcessResult results = processManager.runSync(command, workingDirectory: cwd);
+  final ProcessResult results = processManager.runSync(command, workingDirectory: cwd);
   return results.exitCode == 0 ? results.stdout.trim() : '';
 }