Tweak public APIs and use them in patch_sdk, dart2js, and kernel-service

pkg/kernel/lib/target/targets.dart

 // Copyright (c) 2016, 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 kernel.target.targets;
 
 import '../ast.dart';
 import '../class_hierarchy.dart';
 import '../core_types.dart';
 import '../transformations/treeshaker.dart' show ProgramRoot;
 import 'flutter.dart' show FlutterTarget;
@@ skipping 96 matching lines @@
   /// These transformations should be optimizations and not required for
   /// correctness.  Everything should work if a simple and fast linker chooses
   /// not to apply these transformations.
   ///
   /// Note that [performGlobalTransformations] doesn't have -OnProgram and
   /// -OnLibraries alternatives, because the global knowledge required by the
   /// transformations is assumed to be retrieved from a [Program] instance.
   void performGlobalTransformations(CoreTypes coreTypes, Program program,
       {void logger(String msg)});
 
+  /// Whether a platform library may define a restricted type, such as `bool`,
+  /// `int`, `double`, `num`, and `String`.
+  ///
+  /// By default only `dart:core` may define restricted types, but some target
+  /// implementations override this.
+  bool mayDefineRestrictedType(Uri uri) =>
+      uri.scheme == 'dart' && uri.path == 'core';
+
+  /// Whether the `native` language extension is supported within [library].
+  ///
+  /// The `native` language extension is not part of the language specification,
+  /// it means something else to each target, and it is enabled under different
+  /// circumstances for each target implementation. For example, the VM target
+  /// enables it everywhere because of existing support for "dart-ext:" native
+  /// extensions, but targets like dart2js only enable it on the core libraries.
+  bool enableNative(Uri uri) => false;
+
+  /// There are two variants of the `native` language extension. The VM expects
+  /// the native token to be followed by string, whereas dart2js and DDC do not.
+  // TODO(sigmund, ahe): ideally we should remove the `native` syntax, if not,
+  // we should at least unify the VM and non-VM variants.
+  bool get nativeExtensionExpectsString => false;
+
   /// Builds an expression that instantiates an [Invocation] that can be passed
   /// to [noSuchMethod].
   Expression instantiateInvocation(CoreTypes coreTypes, Expression receiver,
       String name, Arguments arguments, int offset, bool isSuper);
 
   Expression instantiateNoSuchMethodError(CoreTypes coreTypes,
       Expression receiver, String name, Arguments arguments, int offset,
       {bool isMethod: false,
       bool isGetter: false,
       bool isSetter: false,
@@ skipping 65 matching lines @@
       bool isField: false,
       bool isLocalVariable: false,
       bool isDynamic: false,
       bool isSuper: false,
       bool isStatic: false,
       bool isConstructor: false,
       bool isTopLevel: false}) {
     return new InvalidExpression();
   }
 }