Reapply "Use backend targets to run Kernel transformations in Fasta"

pkg/front_end/test/fasta/shaker_test.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.md file.
 
 /// Tests basic functionality of the API tree-shaker.
 ///
 /// Each input file is built and tree-shaken, then we check that the set of
 /// libraries, classes, and members that are retained match those declared in an
 /// expectations file.
 ///
@@ skipping 15 matching lines @@
 import 'package:front_end/src/fasta/kernel/kernel_target.dart'
     show KernelTarget;
 import 'package:front_end/src/fasta/kernel/verifier.dart' show verifyProgram;
 import 'package:front_end/src/fasta/testing/kernel_chain.dart' show runDiff;
 import 'package:front_end/src/fasta/testing/patched_sdk_location.dart';
 import 'package:front_end/src/fasta/ticker.dart' show Ticker;
 import 'package:front_end/src/fasta/translate_uri.dart' show TranslateUri;
 import 'package:front_end/src/fasta/util/relativize.dart' show relativizeUri;
 import 'package:kernel/ast.dart' show Program;
 import 'package:kernel/kernel.dart' show loadProgramFromBytes;
+import 'package:kernel/target/targets.dart' show TargetFlags;
 import 'package:testing/testing.dart'
     show Chain, ChainContext, ExpectationSet, Result, Step, TestDescription;
 import 'testing/suite.dart';
 
 main(List<String> arguments) => runMe(arguments, createContext, "testing.json");
 
 Future<TreeShakerContext> createContext(
     Chain suite, Map<String, String> environment) {
   return TreeShakerContext.create(environment);
 }
@@ skipping 42 matching lines @@
 class BuildProgram
     extends Step<TestDescription, _IntermediateData, TreeShakerContext> {
   const BuildProgram();
   String get name => "build program";
   Future<Result<_IntermediateData>> run(
       TestDescription description, TreeShakerContext context) async {
     try {
       var platformOutline = context.loadPlatformOutline();
       platformOutline.unbindCanonicalNames();
       var dillTarget = new DillTarget(
-          new Ticker(isVerbose: false), context.uriTranslator, "vm");
+          new Ticker(isVerbose: false), context.uriTranslator, "vm_fasta",
+          flags: new TargetFlags(strongMode: false));
       dillTarget.loader.appendLibraries(platformOutline);
-      var sourceTarget = new KernelTarget(PhysicalFileSystem.instance,
-          dillTarget, context.uriTranslator, false);
+      var sourceTarget = new KernelTarget(
+          PhysicalFileSystem.instance, dillTarget, context.uriTranslator);
       await dillTarget.buildOutlines();
 
       var inputUri = description.uri;
 
       /// We treat the lib.dart library as a special dependency that was
       /// previously built. To do so, we build it and append it back to the
       /// dillTarget before building the actual test.
       var libUri = inputUri.resolve('lib/lib.dart');
       sourceTarget.read(libUri);
       dillTarget.loader.appendLibraries(
           await sourceTarget.buildOutlines(), (uri) => uri == libUri);
 
       /// This new KernelTarget contains only sources from the test without
       /// lib.dart.
-      sourceTarget = new KernelTarget(PhysicalFileSystem.instance, dillTarget,
-          context.uriTranslator, false);
+      sourceTarget = new KernelTarget(
+          PhysicalFileSystem.instance, dillTarget, context.uriTranslator);
 
       await dillTarget.buildOutlines();
       sourceTarget.read(inputUri);
       var contents = new File.fromUri(inputUri).readAsStringSync();
       var showCoreLibraries = contents.contains("@@SHOW_CORE_LIBRARIES@@");
 
       await sourceTarget.buildOutlines();
       // Note: We run the tree-shaker as a separate step on this suite to be
       // able to specify what libraries to tree shake (by default only the code
       // in the dillTarget gets tree-shaken). We could apply the tree-shaker
@@ skipping 104 matching lines @@
           """
 Please create file ${expectedFile.path} with this content:
 $buffer""");
     }
   }
 }
 
 /// A special library used only to test the shaker. The suite above will
 /// tree-shake the contents of this library.
 const _specialLibraryPath = 'pkg/front_end/testcases/shaker/lib/lib.dart';