buffer: initialize TextDecoder once on blob.text()

PR-URL: #44787
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>

lib/internal/blob.js

@@ -78,6 +78,7 @@ let ReadableStream;
 let URL;
 
 const enc = new TextEncoder();
+let dec;
 
 // Yes, lazy loading is annoying but because of circular
 // references between the url, internal/blob, and buffer
@@ -311,7 +312,8 @@ class Blob {
     if (!isBlob(this))
       throw new ERR_INVALID_THIS('Blob');
 
-    const dec = new TextDecoder();
+    dec ??= new TextDecoder();
+
     return dec.decode(await this.arrayBuffer());
   }