Import rasta tests.

pkg/fasta/test/rasta/duplicated_mixin.dart.direct.expect

+library;
+import self as self;
+import "dart:core" as core;
+
+class Mixin extends core::Object {
+  field dynamic field;
+  constructor •() → self::Mixin
+    : super core::Object::•();
+}
+class A extends self::Object+Mixin+Mixin#0 {
+  constructor •() → self::A
+    : super self::Object+Mixin+Mixin#0::•();
+}
+abstract class Object+Mixin+Mixin#0 extends self::Object+Mixin#0 implements self::Mixin {
+  field dynamic field;
+  constructor •() → dynamic
+    : super self::Object+Mixin#0::•();
+}
+abstract class Object+Mixin#0 extends core::Object implements self::Mixin {
+  field dynamic field;
+  constructor •() → dynamic
+    : super core::Object::•();
+}