Reduce use of relativize and unsort methods.

pkg/front_end/lib/src/fasta/dill/dill_typedef_builder.dart

Index: pkg/front_end/lib/src/fasta/dill/dill_typedef_builder.dart
diff --git a/pkg/front_end/lib/src/fasta/dill/dill_typedef_builder.dart b/pkg/front_end/lib/src/fasta/dill/dill_typedef_builder.dart
index 07c66c998ab83f35e30e561acb445f124789bba8..929b1690b253646bdbbc9fbf6b8ce2371898de9b 100644
--- a/pkg/front_end/lib/src/fasta/dill/dill_typedef_builder.dart
+++ b/pkg/front_end/lib/src/fasta/dill/dill_typedef_builder.dart
@@ -18,10 +18,9 @@ import '../kernel/kernel_builder.dart'
 import 'dill_library_builder.dart' show DillLibraryBuilder;
 
 class DillFunctionTypeAliasBuilder extends KernelFunctionTypeAliasBuilder {
-  final Typedef typedef;
-
-  DillFunctionTypeAliasBuilder(this.typedef, DillLibraryBuilder parent)
-      : super(null, null, typedef.name, null, null, parent, typedef.fileOffset);
+  DillFunctionTypeAliasBuilder(Typedef typedef, DillLibraryBuilder parent)
+      : super(null, null, typedef.name, null, null, parent, typedef.fileOffset,
+            typedef);
 
   @override
   List<FormalParameterBuilder> get formals {
@@ -43,5 +42,5 @@ class DillFunctionTypeAliasBuilder extends KernelFunctionTypeAliasBuilder {
   }
 
   @override
-  DartType buildThisType(LibraryBuilder library) => typedef.type;
+  DartType buildThisType(LibraryBuilder library) => thisType = target.type;

[Johnni Winther, 2017/05/15 11:43:56]

`thisType = ...` -> `thisType ??= ...`

[ahe, 2017/05/15 11:54:29]

Done.

 }