Downwards inference. This adds support to the resolver for downwards

pkg/analyzer/test/src/task/strong/strong_test_helper.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.
 
 // TODO(jmesserly): this file needs to be refactored, it's a port from
 // package:dev_compiler's tests
 library test.src.task.strong.strong_test_helper;
 
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/file_system/memory_file_system.dart';
@@ skipping 74 matching lines @@
     for (var lib in allLibraries) {
       for (var unit in lib.units) {
         var errors = <AnalysisError>[];
         collector.errors = errors;
 
         var source = unit.source;
         if (source.uri.scheme == 'dart') continue;
 
         var librarySource = context.getLibrariesContaining(source).single;
         var resolved = context.resolveCompilationUnit2(source, librarySource);
+        var analyzerErrors = context
+            .getErrors(source)
+            .errors
+            .where((error) =>
+                error.errorCode.name.startsWith('dev_compiler.InferredType'))
+            .toList();
+        errors.addAll(analyzerErrors);
         checker.visitCompilationUnit(resolved);
 
         new _ExpectedErrorVisitor(errors).validate(resolved);
       }
     }
   });
 }
 
 class _ErrorCollector implements AnalysisErrorListener {
   List<AnalysisError> errors;
@@ skipping 283 matching lines @@
           String toString(){}
           bool ==(other){}
         }
         class Function {}
         class StackTrace {}
         class Symbol {}
         class Type {}
 
         class String {
           String operator +(String other) {}
+          String substring(int len) {}
         }
         class bool {}
         class num {
           num operator +(num other) {}
         }
         class int extends num {
           bool operator<(num other) {}
           int operator-() {}
         }
         class double extends num {}
@@ skipping 83 matching lines @@
   if (levelName == 'warning') return _MAGENTA_COLOR;
   if (levelName == 'info') return _CYAN_COLOR;
   return null;
 }
 
 const String _RED_COLOR = '\u001b[31m';
 const String _MAGENTA_COLOR = '\u001b[35m';
 const String _CYAN_COLOR = '\u001b[36m';
 const String GREEN_COLOR = '\u001b[32m';
 const String NO_COLOR = '\u001b[0m';