Change new List(n) to return fixed length list.

sdk/lib/crypto/sha1.dart

Index: sdk/lib/crypto/sha1.dart
diff --git a/sdk/lib/crypto/sha1.dart b/sdk/lib/crypto/sha1.dart
index af3d35449b874252c25a0c8757034e029e2c6f1e..83e9217806db2c2ecba5a98b926d17903acae42a 100644
--- a/sdk/lib/crypto/sha1.dart
+++ b/sdk/lib/crypto/sha1.dart
@@ -7,7 +7,7 @@ part of dart.crypto;
 // The SHA1 hasher is used to compute an SHA1 message digest.
 class _SHA1 extends _HashBase implements SHA1 {
   // Construct a SHA1 hasher object.
-  _SHA1() : _w = new List.fixedLength(80), super(16, 5, true) {
+  _SHA1() : _w = new List(80), super(16, 5, true) {
     _h[0] = 0x67452301;
     _h[1] = 0xEFCDAB89;
     _h[2] = 0x98BADCFE;