Remove custom expect.dart from Kernel tests

tests/kernel/unsorted/block_scope_test.dart

Index: tests/kernel/unsorted/block_scope_test.dart
diff --git a/tests/kernel/unsorted/block_scope_test.dart b/tests/kernel/unsorted/block_scope_test.dart
index ae54352a81e984cd0fae908eddd1fd02602f7642..36e3d66c2858afb4c3d3fc5c5779e7f5c3a7b9b8 100644
--- a/tests/kernel/unsorted/block_scope_test.dart
+++ b/tests/kernel/unsorted/block_scope_test.dart
@@ -4,7 +4,7 @@
 
 // Tests of block scoping.
 
-import 'expect.dart';
+import 'package:expect/expect.dart';
 
 bool oracle() => true;
 
@@ -57,4 +57,4 @@ test1() {
 main() {
   test0();
   test1();
-}  
+}