Move minitest.dart into the expect package.

pkg/dev_compiler/test/codegen/lib/html/document_test.dart

Index: pkg/dev_compiler/test/codegen/lib/html/document_test.dart
diff --git a/pkg/dev_compiler/test/codegen/lib/html/document_test.dart b/pkg/dev_compiler/test/codegen/lib/html/document_test.dart
index 88c4dec8c0a646978af57f9644e698a837685309..b7d8f609701dd7790a9b1f0eab9fb98bc6715b7d 100644
--- a/pkg/dev_compiler/test/codegen/lib/html/document_test.dart
+++ b/pkg/dev_compiler/test/codegen/lib/html/document_test.dart
@@ -1,6 +1,6 @@
 import 'dart:html';
 
-import 'package:minitest/minitest.dart';
+import 'package:expect/minitest.dart';
 
 main() {
   var isElement = predicate((x) => x is Element, 'is an Element');