Fix failing lints (#2548)

Author: grouma

packages/devtools_app/lib/src/extent_delegate_list.dart

@@ -80,7 +80,7 @@ abstract class FixedExtentDelegateBase extends ExtentDelegate {
     // want to query for _offsets(length) to cheaply determine the total size
     // of the list. Additionally, the logic for binary search assumes that we
     // have one offset past the end of the list.
-    _offsets = List(length + 1);
+    _offsets = List.filled(length + 1, 0.0);
     double offset = 0;
     // The first item in the list is at offset zero.
     // TODO(jacobr): remove this line once we have NNBD lists.

packages/devtools_app/lib/src/memory/memory_graph_model.dart

@@ -120,7 +120,7 @@ HeapGraph convertHeapGraph(
 
   // Construct all the classes in the snapshot.
   final List<HeapGraphClassLive> classes =
-      List<HeapGraphClassLive>(graph.classes.length);
+      List<HeapGraphClassLive>.filled(graph.classes.length, null);
   for (int i = 0; i < graph.classes.length; i++) {
     final HeapSnapshotClass c = graph.classes[i];
 
@@ -148,7 +148,7 @@ HeapGraph convertHeapGraph(
 
   // Pre-allocate the number of objects in the snapshot.
   final List<HeapGraphElementLive> elements =
-      List<HeapGraphElementLive>(graph.objects.length);
+      List<HeapGraphElementLive>.filled(graph.objects.length, null);
 
   // Construct all objects.
   for (int i = 0; i < graph.objects.length; i++) {
@@ -188,7 +188,8 @@ HeapGraph convertHeapGraph(
   final snapshotExternals = graph.externalProperties;
 
   // Pre-allocate the number of external objects in the snapshot.
-  final externals = List<HeapGraphExternalLive>(snapshotExternals.length);
+  final externals =
+      List<HeapGraphExternalLive>.filled(snapshotExternals.length, null);
 
   // Construct all external objects and link to its live element.
   for (int index = 0; index < snapshotExternals.length; index++) {

packages/devtools_app/lib/src/scaffold.dart

@@ -293,6 +293,8 @@ class DevToolsScaffoldState extends State<DevToolsScaffold>
         ),
     ];
 
+    // TODO(issues/2547) - Remove.
+    // ignore: deprecated_member_use
     return ValueListenableProvider.value(
       value: _currentScreen,
       child: Provider<BannerMessagesController>(