Canonicalize mixin applications by their name

pkg/front_end/test/fasta/mixin.dart.outline.expect

Index: pkg/front_end/test/fasta/mixin.dart.outline.expect
diff --git a/pkg/front_end/test/fasta/mixin.dart.outline.expect b/pkg/front_end/test/fasta/mixin.dart.outline.expect
index 7c0c30a4736cc9b5e81af0c377ebe7cd5de2f4c0..cdba6feedc4f069c89b6c06587ae244390262a16 100644
--- a/pkg/front_end/test/fasta/mixin.dart.outline.expect
+++ b/pkg/front_end/test/fasta/mixin.dart.outline.expect
@@ -36,10 +36,6 @@ abstract class Object&M1 = core::Object with self::M1 {
 }
 abstract class Object&M1&M2 = self::Object&M1 with self::M2 {
 }
-abstract class Object&M1 = core::Object with self::M1 {
-}
-abstract class Object&M1&M2 = self::Object&M1 with self::M2 {
-}
 abstract class D^G1<S extends core::Object> = core::Object with self::G1<self::D^G1::S> {
 }
 static method main() → dynamic