pkg/crypto: move tests to unittest package

pkg/crypto/lib/src/sha1.dart

Index: pkg/crypto/lib/src/sha1.dart
diff --git a/pkg/crypto/lib/src/sha1.dart b/pkg/crypto/lib/src/sha1.dart
index f08c987c0321d3c036f9086bdb15cf8d95c2da7d..0b55b8d2dbbf6a4303c2a3c1ef5b70976cff37bb 100644
--- a/pkg/crypto/lib/src/sha1.dart
+++ b/pkg/crypto/lib/src/sha1.dart
@@ -8,6 +8,8 @@ part of crypto;
  * SHA1 hash function implementation.
  */
 class SHA1 extends _HashBase {
+  final List<int> _w;
+
   // Construct a SHA1 hasher object.
   SHA1() : _w = new List(80), super(16, 5, true) {
     _h[0] = 0x67452301;
@@ -64,6 +66,4 @@ class SHA1 extends _HashBase {
     _h[3] = _add32(d, _h[3]);
     _h[4] = _add32(e, _h[4]);
   }
-
-  List<int> _w;
 }