combinator suggestion fix and more common tests

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

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library services.completion.computer.dart.local;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/protocol.dart' as protocol show Element,
     ElementKind;
@@ skipping 67 matching lines @@
               }
             });
           }
         }
       }
     });
     visitNode(node);
   }
 
   @override
+  Future<bool> visitCombinator(Combinator node) {
+    // Handled by ImportedComputer
+  }
+
+  @override
   visitCascadeExpression(CascadeExpression node) {
     Expression target = node.target;
     // This computer handles the expression
     // while InvocationComputer handles the cascade selector
     if (target != null && request.offset <= target.end) {
       visitNode(node);
     }
   }
 
   @override
@@ skipping 373 matching lines @@
     if (name == null || name.length <= 0) {
       return DYNAMIC;
     }
     TypeArgumentList typeArgs = type.typeArguments;
     if (typeArgs != null) {
       //TODO (danrubel) include type arguments
     }
     return name;
   }
 }