Use TextDecoder for toString('utf8')

Author: mischnic

index.js

@@ -522,7 +522,7 @@ function slowToString (encoding, start, end) {
 
       case 'utf8':
       case 'utf-8':
-        return utf8Slice(this, start, end)
+        return new TextDecoder(encoding).decode(this.slice(start, end))
 
       case 'ascii':
         return asciiSlice(this, start, end)