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

pkg/front_end/lib/src/fasta/kernel/kernel_target.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.kernel_target;
 
 import 'dart:async' show Future;
 
 import 'dart:io' show File;
 
@@ skipping 22 matching lines @@
         Program,
         Source,
         StringLiteral,
         SuperInitializer,
         Throw,
         TypeParameter,
         VariableDeclaration,
         VariableGet,
         VoidType;
 
-import 'package:kernel/transformations/erasure.dart' show Erasure;
-
-import 'package:kernel/transformations/continuation.dart' as transformAsync;
-
-import 'package:kernel/transformations/mixin_full_resolution.dart' as mix;
-
 import 'package:kernel/type_algebra.dart' show substitute;
 
 import '../source/source_loader.dart' show SourceLoader;
 
 import '../source/source_class_builder.dart' show SourceClassBuilder;
 
 import '../target_implementation.dart' show TargetImplementation;
 
 import '../translate_uri.dart' show TranslateUri;
 
@@ skipping 23 matching lines @@
         TypeVariableBuilder;
 
 import 'verifier.dart' show verifyProgram;
 import 'kernel_outline_shaker.dart'
     show trimProgram, RetainedDataBuilder, RootsMarker;
 
 class KernelTarget extends TargetImplementation {
   /// The [FileSystem] which should be used to access files.
   final FileSystem fileSystem;
 
-  final bool strongMode;
-
   final DillTarget dillTarget;
 
   /// Shared with [CompilerContext].
   final Map<String, Source> uriToSource;
 
   SourceLoader<Library> loader;
 
   Program program;
 
   final List<String> errors = <String>[];
 
   final TypeBuilder dynamicType =
       new KernelNamedTypeBuilder("dynamic", null, -1, null);
 
-  KernelTarget(this.fileSystem, DillTarget dillTarget,
-      TranslateUri uriTranslator, this.strongMode,
+  bool get strongMode => backendTarget.strongMode;
+
+  KernelTarget(
+      this.fileSystem, DillTarget dillTarget, TranslateUri uriTranslator,
       [Map<String, Source> uriToSource])
       : dillTarget = dillTarget,
         uriToSource = uriToSource ?? CompilerContext.current.uriToSource,
         super(dillTarget.ticker, uriTranslator, dillTarget.backendTarget) {
     resetCrashReporting();
     loader = createLoader();
   }
 
   void addError(file, int charOffset, String message) {
     Uri uri = file is String ? Uri.parse(file) : file;
@@ skipping 528 matching lines @@
           initializer.parent = constructor;
           constructor.initializers.insert(0, initializer);
         }
       }
     });
   }
 
   /// Run all transformations that are needed when building a program for the
   /// first time.
   void runBuildTransformations() {
-    transformMixinApplications();
-    otherTransformations();
-  }
-
-  void transformMixinApplications() {
-    mix.transformLibraries(
-        backendTarget, loader.coreTypes, loader.hierarchy, loader.libraries);
-    ticker.logMs("Transformed mixin applications");
-  }
-
-  void otherTransformations() {
-    if (!strongMode) {
-      // TODO(ahe): Don't generate type variables in the first place.
-      program.accept(new Erasure());
-      ticker.logMs("Erased type variables in generic methods");
-    }
-    if (errors.isEmpty && loader.collectCompileTimeErrors().isEmpty) {
-      // TODO(kmillikin): Make this run on a per-method basis.
-      transformAsync.transformLibraries(loader.coreTypes, loader.libraries);
-    }
-    ticker.logMs("Transformed async methods");
+    backendTarget.performModularTransformationsOnLibraries(
+        loader.coreTypes, loader.hierarchy, loader.libraries,
+        logger: (String msg) => ticker.logMs(msg));
+    backendTarget.performGlobalTransformations(loader.coreTypes, program,
+        logger: (String msg) => ticker.logMs(msg));
   }
 
   void verify() {
     var verifyErrors = verifyProgram(program);
     errors.addAll(verifyErrors.map((error) => '$error'));
     ticker.logMs("Verified program");
   }
 
   /// Tree-shakes most code from the [dillTarget] by visiting all other
   /// libraries in [program] and marking the APIs from the [dillTarget]
@@ skipping 33 matching lines @@
   }
   for (Constructor constructor in superclass.constructors) {
     if (constructor.name.name.isEmpty) {
       return constructor.function.requiredParameterCount == 0
           ? constructor
           : null;
     }
   }
   return null;
 }