fixes #27586, prefer context type in generic inference

pkg/analyzer/lib/src/error/codes.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 analyzer.src.error.codes;
 
 import 'package:analyzer/error/error.dart';
 
 export 'package:analyzer/src/analysis_options/error/option_codes.dart';
 export 'package:analyzer/src/dart/error/hint_codes.dart';
@@ skipping 4713 matching lines @@
 
   static const StrongModeCode INVALID_PARAMETER_DECLARATION =
       const StrongModeCode(
           ErrorType.COMPILE_TIME_ERROR,
           'INVALID_PARAMETER_DECLARATION',
           "Type check failed: '{0}' isn't of type '{1}'.");
 
   static const StrongModeCode COULD_NOT_INFER = const StrongModeCode(
       ErrorType.COMPILE_TIME_ERROR,
       'COULD_NOT_INFER',
-      "Couldn't infer type parameter '{0}'; '{1}' must be of type '{2}'.");
+      "Couldn't infer type parameter '{0}'.{1}");
 
   static const StrongModeCode INFERRED_TYPE = const StrongModeCode(
       ErrorType.HINT, 'INFERRED_TYPE', _inferredTypeMessage);
 
   static const StrongModeCode INFERRED_TYPE_LITERAL = const StrongModeCode(
       ErrorType.HINT, 'INFERRED_TYPE_LITERAL', _inferredTypeMessage);
 
   static const StrongModeCode INFERRED_TYPE_ALLOCATION = const StrongModeCode(
       ErrorType.HINT, 'INFERRED_TYPE_ALLOCATION', _inferredTypeMessage);
 
@@ skipping 160 matching lines @@
    * created from the optional [correction] template.
    */
   const StrongModeCode(ErrorType type, String name, String message,
       [String correction])
       : type = type,
         super('STRONG_MODE_$name', message, correction);
 
   @override
   ErrorSeverity get errorSeverity => type.severity;
 }