include imported elements in interpolation suggestions

pkg/analysis_server/lib/src/services/completion/imported_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.toplevel;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/protocol_server.dart' hide Element,
     ElementKind;
@@ skipping 86 matching lines @@
   @override
   Future<bool> visitForStatement(ForStatement node) {
     Token leftParenthesis = node.leftParenthesis;
     if (leftParenthesis != null && request.offset >= leftParenthesis.end) {
       return _addImportedElementSuggestions();
     }
     return new Future.value(false);
   }
 
   @override
+  Future<bool> visitInterpolationExpression(InterpolationExpression node) {
+    Expression expression = node.expression;
+    if (expression is SimpleIdentifier) {
+      return _addImportedElementSuggestions();
+    }
+    return new Future.value(false);
+  }
+
+  @override
   Future<bool> visitNode(AstNode node) {
     return new Future.value(false);
   }
 
   @override
   Future<bool> visitPrefixedIdentifier(PrefixedIdentifier node) {
     // Make suggestions for the prefix, but not for the selector
     // InvocationComputer makes selector suggestions
     Token period = node.period;
     if (period != null && request.offset <= period.offset) {
@@ skipping 159 matching lines @@
           importElem.isDeprecated,
           false);
       LibraryElement lib = importElem.importedLibrary;
       if (lib != null) {
         suggestion.element = newElement_fromEngine(lib);
       }
       request.suggestions.add(suggestion);
     }
   }
 }