lib/encoding/base64: clear() via array-decay now that #258 lands; drop stale comment

lib/encoding/base64/base64.ww

@@ -246,16 +246,10 @@ fn encode_closer(s: io.stream) (void | io.error) = {
 };
 
 // clear — zero the work buffers after a flush.
-// ref/hare/encoding/base64/base64.ha:244-247. Hare passes the bare
-// arrays (`bytes::zero(e.ibuf)`) which array-decay to a WHOLE-array
-// slice — a hygiene wipe of every byte. ww has no implicit [N]T->[]T
-// coercion yet (#258), so the slices are spelled EXPLICIT and
-// FULL-LENGTH (`[0:len(...)]`, length via len() per rule-13) to
-// preserve Hare's whole-array wipe; a windowed slice would leave stale
-// tail bytes (a behavioral divergence).
+// ref/hare/encoding/base64/base64.ha:244-247.
 fn clear(e: *encoder) void = {
-	bytes.zero(e.ibuf[0 : len(e.ibuf)]);
-	bytes.zero(e.obuf[0 : len(e.obuf)]);
+	bytes.zero(e.ibuf);
+	bytes.zero(e.obuf);
 };
 
 // encodeslice — encode `in` and return a fresh byte slice of base64