move import combinator suggestions into a separate computer

pkg/analysis_server/lib/src/services/completion/dart_completion_manager.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 test.services.completion.dart;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/protocol.dart';
+import 'package:analysis_server/src/services/completion/combinator_computer.dart';
 import 'package:analysis_server/src/services/completion/completion_manager.dart';
 import 'package:analysis_server/src/services/completion/imported_computer.dart';
 import 'package:analysis_server/src/services/completion/invocation_computer.dart';
 import 'package:analysis_server/src/services/completion/keyword_computer.dart';
 import 'package:analysis_server/src/services/completion/local_computer.dart';
 import 'package:analysis_server/src/services/search/search_engine.dart';
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/element.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/source.dart';
@@ skipping 66 matching lines @@
     waitForAnalysis().then((CompilationUnit unit) {
       if (unit == null) {
         sendResults(true);
         return;
       }
       request.unit = unit;
       request.node = new NodeLocator.con1(offset).searchWithin(unit);
       int count = computers.length;
       computers.forEach((c) {
         c.computeFull(request).then((bool changed) {
-          var last = --count == 0;
+          bool last = --count == 0;
           if (changed || last) {
             sendResults(last);
           }
         });
       });
     });
   }
 
   /**
    * Build and initialize the list of completion computers
    */
   void initComputers() {
     if (computers == null) {
       computers = [
           new KeywordComputer(),
           new LocalComputer(),
+          new CombinatorComputer(),
           new ImportedComputer(),
           new InvocationComputer()];
     }
   }
 
   /**
    * Send the current list of suggestions to the client.
    */
   void sendResults(bool last) {
     controller.add(
@@ skipping 98 matching lines @@
   _ReplacementOffsetBuilder(this.request) {
     request.replacementOffset = request.offset;
     request.replacementLength = 0;
   }
 
   visitSimpleIdentifier(SimpleIdentifier node) {
     request.replacementOffset = node.offset;
     request.replacementLength = node.length;
   }
 }