cleanup warnings

pkg/analysis_server/lib/src/services/completion/invocation_computer.dart

Index: pkg/analysis_server/lib/src/services/completion/invocation_computer.dart
diff --git a/pkg/analysis_server/lib/src/services/completion/invocation_computer.dart b/pkg/analysis_server/lib/src/services/completion/invocation_computer.dart
index ff2b40ae76ac7c990d5dd18ad412391a36116e19..7191f4ee87b7c84ed583774594254f9d8421fbbb 100644
--- a/pkg/analysis_server/lib/src/services/completion/invocation_computer.dart
+++ b/pkg/analysis_server/lib/src/services/completion/invocation_computer.dart
@@ -55,9 +55,9 @@ class _ExpressionSuggestionBuilder implements SuggestionBuilder {
       node = node.parent;
     }
     if (node is MethodInvocation) {
-      node = node.realTarget;
+      node = (node as MethodInvocation).realTarget;
     } else if (node is PropertyAccess) {
-      node = node.realTarget;
+      node = (node as PropertyAccess).realTarget;
     }
     if (node is Expression) {
       DartType type = node.bestType;