Remove ShadowVariableDeclaration.isSemiSafe.

pkg/front_end/lib/src/fasta/kernel/kernel_shadow_ast.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.
 
 /// This file declares a "shadow hierarchy" of concrete classes which extend
 /// the kernel class hierarchy, adding methods and fields needed by the
 /// BodyBuilder.
 ///
 /// Instances of these classes may be created using the factory methods in
 /// `ast_factory.dart`.
@@ skipping 2360 matching lines @@
   final bool _implicitlyTyped;
 
   final int _functionNestingLevel;
 
   bool _mutatedInClosure = false;
 
   bool _mutatedAnywhere = false;
 
   final bool _isLocalFunction;
 
-  /// If this variable declaration represents a formal parameter, indicates
-  /// whether uses of it need to be type-checked due to the covariance of class
-  /// type parameters.
-  ///
-  /// TODO(paulberry): replace this with an enum so that it can represent
-  /// "unsafe" parameters as well.
-  ///
-  /// TODO(paulberry): remove this once there is a corresponding annotation in
-  /// the kernel representation.
-  bool isSemiSafe = false;
-
   ShadowVariableDeclaration(String name, this._functionNestingLevel,
       {Expression initializer,
       DartType type,
       bool isFinal: false,
       bool isConst: false,
       bool isFieldFormal: false,
       bool isCovariant: false,
       bool isLocalFunction: false})
       : _implicitlyTyped = type == null,
         _isLocalFunction = isLocalFunction,
@@ skipping 118 matching lines @@
   accept(v) => unsupported("accept", -1, null);
 
   accept1(v, arg) => unsupported("accept1", -1, null);
 
   getStaticType(types) => unsupported("getStaticType", -1, null);
 
   transformChildren(v) => unsupported("transformChildren", -1, null);
 
   visitChildren(v) => unsupported("visitChildren", -1, null);
 }