extract named constructor suggestions from prefixed element contributor

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

Index: pkg/analysis_server/lib/src/services/completion/dart/completion_manager.dart
diff --git a/pkg/analysis_server/lib/src/services/completion/dart/completion_manager.dart b/pkg/analysis_server/lib/src/services/completion/dart/completion_manager.dart
index 6f182d813487e9dfbb72823ce03eeff57dff2962..904f1c210db9466e84abd2670a8b8ad8f496fb46 100644
--- a/pkg/analysis_server/lib/src/services/completion/dart/completion_manager.dart
+++ b/pkg/analysis_server/lib/src/services/completion/dart/completion_manager.dart
@@ -22,6 +22,7 @@ import 'package:analyzer/src/generated/engine.dart' hide AnalysisContextImpl;
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/task/dart.dart';
 import 'package:analyzer/task/dart.dart';
+import 'package:analyzer/src/generated/element.dart';
 
 /**
  * [DartCompletionManager] determines if a completion request is Dart specific
@@ -99,6 +100,20 @@ class DartCompletionRequestImpl extends CompletionRequestImpl
   }
 
   @override
+  Future<LibraryElement> resolveContainingLibrary() async {

[scheglov, 2015/12/07 16:16:15]

It seems that the documentation for the method and its implementation don't
agree.
This method does not return the fully resolved LibraryElement.
But the documentation does not mention this.

[danrubel, 2015/12/07 16:59:38]

Good point. This is not meant to resolve the library element, just return it. 
Renamed accessor to `libraryElement` and updated doc to reflect this.

+    //TODO(danrubel) resolve the library element
+    // rather than all the declarations
+    CompilationUnit unit = await resolveDeclarationsInScope();
+    if (unit != null) {
+      CompilationUnitElement elem = unit.element;
+      if (elem != null) {
+        return elem.library;
+      }
+    }
+    return null;
+  }
+
+  @override
   Future<CompilationUnit> resolveDeclarationsInScope() async {
     CompilationUnit unit = target.unit;
     if (_haveResolveDeclarationsInScope) {