Finish strong mode cleaning of dart2js.

pkg/compiler/lib/src/inferrer/type_graph_dump.dart

Index: pkg/compiler/lib/src/inferrer/type_graph_dump.dart
diff --git a/pkg/compiler/lib/src/inferrer/type_graph_dump.dart b/pkg/compiler/lib/src/inferrer/type_graph_dump.dart
index f79637bd28c851f06f7781e1ab9ba192d8ae3b6b..c1a19fa2839c1fd79e759b00efe85d2b2305fdeb 100644
--- a/pkg/compiler/lib/src/inferrer/type_graph_dump.dart
+++ b/pkg/compiler/lib/src/inferrer/type_graph_dump.dart
@@ -296,7 +296,7 @@ class _GraphGenerator extends TypeInformationVisitor {
       append('$id [shape=record,label="$label",$style]');
       // Add assignment edges. Color the edges based on whether they were
       // added, removed, temporary, or unchanged.
-      var originalSet = global.assignmentsBeforeAnalysis[node] ?? const [];
+      dynamic originalSet = global.assignmentsBeforeAnalysis[node] ?? const [];
       var tracerSet = global.assignmentsBeforeTracing[node] ?? const [];
       var currentSet = node.assignments.toSet();
       for (TypeInformation assignment in currentSet) {