prefer_contains (#8040)

dev/devicelab/lib/framework/utils.dart

@@ -125,9 +125,9 @@ Future<String> getDartVersion() async {
   //   Dart VM version: 1.17.0-dev.2.0 (Tue May  3 12:14:52 2016) on "macos_x64"
   // to:
   //   1.17.0-dev.2.0
-  if (version.indexOf('(') != -1)
+  if (version.contains('('))
     version = version.substring(0, version.indexOf('(')).trim();
-  if (version.indexOf(':') != -1)
+  if (version.contains(':'))
     version = version.substring(version.indexOf(':') + 1).trim();
 
   return version.replaceAll('"', "'");

packages/flutter_tools/lib/src/commands/daemon.dart

@@ -127,7 +127,7 @@ class Daemon {
 
     try {
       String method = request['method'];
-      if (method.indexOf('.') == -1)
+      if (!method.contains('.'))
         throw 'method not understood: $method';
 
       String prefix = method.substring(0, method.indexOf('.'));