Instrument analyzer's type analysis and run front_end inference tests.

pkg/front_end/lib/src/base/instrumentation.dart

 // Copyright (c) 2017, 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.
 
 import 'package:kernel/ast.dart';
 
 /// Interface providing the ability to record property/value pairs associated
 /// with source file locations.  Intended to facilitate testing.
 abstract class Instrumentation {
   /// Records a property/value pair associated with the given URI and offset.
@@ skipping 17 matching lines @@
 
 /// Instance of [InstrumentationValue] describing a [DartType].
 class InstrumentationValueForType extends InstrumentationValue {
   final DartType type;
 
   InstrumentationValueForType(this.type);
 
   @override
   String toString() {
     // Convert '→' to '->' because '→' doesn't show up in some terminals.
-    return type.toString().replaceAll('→', '->');
+    // Remove prefixes that are used very often in tests.
+    return type
+        .toString()
+        .replaceAll('→', '->')
+        .replaceAll('dart.core::', '')
+        .replaceAll('dart.async::', '')
+        .replaceAll('test::', '');
   }
 }
 
 /// Instance of [InstrumentationValue] which only matches the given literal
 /// string.
 class InstrumentationValueLiteral extends InstrumentationValue {
   final String value;
 
   const InstrumentationValueLiteral(this.value);
 
   @override
   String toString() => value;
 }