combinator suggestion fix and more common tests

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

Index: pkg/analysis_server/lib/src/services/completion/local_computer.dart
diff --git a/pkg/analysis_server/lib/src/services/completion/local_computer.dart b/pkg/analysis_server/lib/src/services/completion/local_computer.dart
index aedc167f74b32b7623a505036b2acf00f9d0aab2..88829f1b8bbb9aec3ebb9b9f59edf09a2ac7f277 100644
--- a/pkg/analysis_server/lib/src/services/completion/local_computer.dart
+++ b/pkg/analysis_server/lib/src/services/completion/local_computer.dart
@@ -85,6 +85,11 @@ class _LocalVisitor extends GeneralizingAstVisitor<dynamic> {
   }
 
   @override
+  Future<bool> visitCombinator(Combinator node) {
+    // Handled by ImportedComputer
+  }
+
+  @override
   visitCascadeExpression(CascadeExpression node) {
     Expression target = node.target;
     // This computer handles the expression