Fix reference sharing in the event that import prefixes are used.

pkg/analyzer/test/src/summary/summary_common.dart

 // Copyright (c) 2015, 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 analyzer.test.src.summary.summary_common;
 
 import 'package:analyzer/analyzer.dart';
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/src/dart/scanner/reader.dart';
@@ skipping 7664 matching lines @@
     UnlinkedClass cls =
         serializeClassText('class C { final x = <dynamic, int>{}; }');
     EntityRef type = getTypeRefForSlot(cls.fields[0].inferredTypeSlot);
     // Check that x has inferred type `Map<dynamic, int>`.
     checkLinkedTypeRef(type, 'dart:core', 'dart:core', 'Map',
         numTypeParameters: 2, numTypeArguments: 2);
     checkLinkedTypeRef(type.typeArguments[0], null, null, 'dynamic');
     checkLinkedTypeRef(type.typeArguments[1], 'dart:core', 'dart:core', 'int');
   }
 
+  test_inferred_type_reference_shared_prefixed() {
+    if (!strongMode || skipFullyLinkedData) {
+      return;
+    }
+    // Variable `y` has an inferred type of `p.C`.  Verify that the reference
+    // used by the explicit type of `x` is re-used for the inferred type.
+    addNamedSource('/a.dart', 'class C {}');
+    serializeLibraryText('import "a.dart" as p; p.C x; var y = new p.C();');
+    EntityRef xType = findVariable('x').type;
+    EntityRef yType = getTypeRefForSlot(findVariable('y').inferredTypeSlot);
+    expect(yType.reference, xType.reference);
+  }
+
   test_inferred_type_refers_to_bound_type_param() {
     if (!strongMode || skipFullyLinkedData) {
       return;
     }
     UnlinkedClass cls = serializeClassText(
         'class C<T> extends D<int, T> { var v; }'
         ' abstract class D<U, V> { Map<V, U> get v; }',
         className: 'C');
     EntityRef type = getTypeRefForSlot(cls.fields[0].inferredTypeSlot);
     // Check that v has inferred type Map<T, int>.
@@ skipping 2278 matching lines @@
 class _PrefixExpectation {
   final ReferenceKind kind;
   final String name;
   final String absoluteUri;
   final String relativeUri;
   final int numTypeParameters;
 
   _PrefixExpectation(this.kind, this.name,
       {this.absoluteUri, this.relativeUri, this.numTypeParameters: 0});
 }