Add 'flutter_release' patch_sdk mode to patch_sdk

pkg/kernel/lib/target/targets.dart

Index: pkg/kernel/lib/target/targets.dart
diff --git a/pkg/kernel/lib/target/targets.dart b/pkg/kernel/lib/target/targets.dart
index c47c117fe972d1c61487e542d1d93fa44f648396..7e19da649915ad9f9eb4f0dfa7361e82eb800a23 100644
--- a/pkg/kernel/lib/target/targets.dart
+++ b/pkg/kernel/lib/target/targets.dart
@@ -8,7 +8,7 @@ import '../class_hierarchy.dart';
 import '../core_types.dart';
 import '../transformations/treeshaker.dart' show ProgramRoot;
 import 'flutter.dart' show FlutterTarget;
-import 'flutter_fasta.dart' show FlutterFastaTarget;
+import 'flutter_fasta.dart' show FlutterFastaTarget, FlutterFastaReleaseTarget;
 import 'vm.dart' show VmTarget;
 import 'vm_fasta.dart' show VmFastaTarget;
 import 'vmcc.dart' show VmClosureConvertedTarget;
@@ -39,6 +39,8 @@ final Map<String, _TargetBuilder> targets = <String, _TargetBuilder>{
   'vmreify': (TargetFlags flags) => new VmGenericTypesReifiedTarget(flags),
   'flutter': (TargetFlags flags) => new FlutterTarget(flags),
   'flutter_fasta': (TargetFlags flags) => new FlutterFastaTarget(flags),
+  'flutter_fasta_release': (TargetFlags flags) =>
+      new FlutterFastaReleaseTarget(flags),
 };
 
 Target getTarget(String name, TargetFlags flags) {