Move enableNative to target, turn it on by default

pkg/front_end/lib/src/fasta/kernel/body_builder.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 fasta.body_builder;
 
 import '../fasta_codes.dart'
     show FastaMessage, codeExpectedButGot, codeExpectedFunctionBody;
 
 import '../parser/parser.dart' show FormalParameterType, MemberKind, optional;
@@ skipping 133 matching lines @@
       this.formalParameterScope,
       this.hierarchy,
       this.coreTypes,
       this.classBuilder,
       this.isInstanceMember,
       this.uri,
       this._typeInferrer,
       {this.fieldDependencies})
       : enclosingScope = scope,
         library = library,
-        enableNative = (library.uri.scheme == "dart" || library.isPatch),
+        enableNative = library.loader.target.enableNative(library),
         needsImplicitSuperInitializer =
             coreTypes.objectClass != classBuilder?.cls,
         typePromoter = _typeInferrer.typePromoter,
         super(scope);
 
   bool get hasParserError => recoverableErrors.isNotEmpty;
 
   bool get inConstructor {
     return functionNestingLevel == 0 && member is KernelConstructorBuilder;
   }
@@ skipping 739 matching lines @@
             "Deferred loading isn't implemented yet.", offsetForToken(token));
       } else if (!isQualified && isInstanceContext) {
         assert(builder == null);
         if (constantExpressionRequired) {
           return new UnresolvedAccessor(this, n, token);
         }
         return new ThisPropertyAccessor(this, token, n, null, null);
       } else if (
           // Optimization, if [enableNative] is false, this can't be
           // dart:_builtin.
           enableNative &&

[Siggi Cherem (dart-lang), 2017/05/30 20:33:59]

let me know if you want to drop this optimization now (for the VM this is always
true).

I kept it because it helps with dart2js

[ahe, 2017/05/31 09:07:50]

It's not an optimization anymore. I think we should add a boolean to this class:

final isPlatformLibrary = library.uri.scheme == "dart";

[Siggi Cherem (dart-lang), 2017/05/31 20:26:14]

done. Any reason why not take it a step further and simply add:
  final isBuiltInLibrary = library.uri.scheme == 'dart' && library.uri.path ==
'_builtin';?

[ahe, 2017/06/01 12:20:51]

That's a good idea.

               name == "main" &&
               library.uri.scheme == "dart" &&
               library.uri.path == "_builtin" &&
               member?.name == "_getMainClosure") {
         // TODO(ahe): https://github.com/dart-lang/sdk/issues/28989
         return new KernelNullLiteral()..fileOffset = offsetForToken(token);
       } else {
         return new UnresolvedAccessor(this, n, token);
       }
     } else if (builder.isTypeDeclaration) {
@@ skipping 2316 matching lines @@
     if (starToken == null) {
       return AsyncMarker.Async;
     } else {
       assert(identical(starToken.stringValue, "*"));
       return AsyncMarker.AsyncStar;
     }
   } else {
     return internalError("Unknown async modifier: $asyncToken");
   }
 }