Simplify attribute unpickler

Author: nicolasstucki

compiler/src/dotty/tools/dotc/core/tasty/AttributeUnpickler.scala

@@ -14,11 +14,9 @@ class AttributeUnpickler(reader: TastyReader):
     val attributesBuilder = List.newBuilder[String]
     while (!isAtEnd) {
       val length = readNat()
-      if (length > 0) {
-        val bytes = readBytes(length)
-        val attribute = new String(bytes, StandardCharsets.UTF_8)
-        attributesBuilder += attribute
-      }
+      val bytes = readBytes(length)
+      val attribute = new String(bytes, StandardCharsets.UTF_8)
+      attributesBuilder += attribute
     }
     attributesBuilder.result()
   }