Fix type warnings and a few other warnings, and probably even an error.

lib/compiler/implementation/tree/unparser.dart

Index: lib/compiler/implementation/tree/unparser.dart
diff --git a/lib/compiler/implementation/tree/unparser.dart b/lib/compiler/implementation/tree/unparser.dart
index 7b4c63c58a8ad94bbc6b6475319f772ec4655a2f..9aaad5f83ccd6deef031c158a2a2ba0282cca91f 100644
--- a/lib/compiler/implementation/tree/unparser.dart
+++ b/lib/compiler/implementation/tree/unparser.dart
@@ -32,6 +32,14 @@ class Unparser implements Visitor {
     visit(node.statements);
   }
 
+  visitCascade(Cascade node) {
+    visit(node.expression);
+  }
+
+  visitCascadeReceiver(CascadeReceiver node) {
+    visit(node.expression);
+  }
+
   visitClassNode(ClassNode node) {
     node.beginToken.value.printOn(sb);
     sb.add(' ');