Bug 1856240 - Delete out[i] since its never used. r=sylvestre

Depends on D192310

Differential Revision: https://phabricator.services.mozilla.com/D192314

media/gmp-clearkey/0.1/ClearKeyUtils.cpp

@@ -252,7 +252,6 @@ static bool EncodeBase64Web(vector<uint8_t> aBinary, string& aEncoded) {
 
     // out of bounds index for 'sAlphabet'
     assert(idx < MOZ_ARRAY_LENGTH(sAlphabet));
-    out[i] = sAlphabet[idx];
   }
 
   return true;