add missing type parameter on methods (#22096)

packages/flutter_tools/lib/src/vmservice.dart

diff --git a/packages/flutter_tools/lib/src/vmservice.dart b/packages/flutter_tools/lib/src/vmservice.dart
index 3fc389a..ae7652e 100644
--- a/packages/flutter_tools/lib/src/vmservice.dart
+++ b/packages/flutter_tools/lib/src/vmservice.dart
@@ -289,7 +289,7 @@
     String method,
     Map<String, dynamic> params,
   ) {
-    return Future.any(<Future<Map<String, dynamic>>>[
+    return Future.any<Map<String, dynamic>>(<Future<Map<String, dynamic>>>[
       _peer.sendRequest(method, params).then<Map<String, dynamic>>(castStringKeyedMap),
       _connectionError.future,
     ]);
@@ -954,7 +954,7 @@
       return;
     _viewCache.clear();
     for (Isolate isolate in isolates.toList()) {
-      await vmService.vm.invokeRpc('_flutter.listViews',
+      await vmService.vm.invokeRpc<ServiceObject>('_flutter.listViews',
           timeout: kLongRequestTimeout,
           params: <String, dynamic> {'isolateId': isolate.id});
     }
@@ -1208,7 +1208,7 @@
       <Future<ProgramElement>>[];
     for (Map<String, dynamic> element in response['unused'])
       unusedElements.add(_describeElement(element));
-    return Future.wait(unusedElements);
+    return Future.wait<ProgramElement>(unusedElements);
   }
 
   /// Resumes the isolate.
@@ -1388,7 +1388,7 @@
   @override
   void removeWhere(bool test(String key, dynamic value)) => _map.removeWhere(test);
   @override
-  Map<K2, V2> map<K2, V2>(MapEntry<K2, V2> transform(String key, dynamic value)) => _map.map(transform);
+  Map<K2, V2> map<K2, V2>(MapEntry<K2, V2> transform(String key, dynamic value)) => _map.map<K2, V2>(transform);
   @override
   Iterable<MapEntry<String, dynamic>> get entries => _map.entries;
   @override
@@ -1440,7 +1440,7 @@
 
   Future<Null> setAssetDirectory(Uri assetsDirectory) async {
     assert(assetsDirectory != null);
-    await owner.vmService.vm.invokeRpc('_flutter.setAssetBundlePath',
+    await owner.vmService.vm.invokeRpc<ServiceObject>('_flutter.setAssetBundlePath',
         params: <String, dynamic>{
           'isolateId': _uiIsolate.id,
           'viewId': id,