[jsinterp] Fix increment/decrement evaluation (#13238)

Closes #13241
Authored by: seproDev, bashonly

Co-authored-by: bashonly <88596187+bashonly@users.noreply.github.com>

test/test_youtube_signature.py

@@ -316,6 +316,10 @@ _NSIG_TESTS = [
         'https://www.youtube.com/s/player/8a8ac953/tv-player-es6.vflset/tv-player-es6.js',
         'MiBYeXx_vRREbiCCmh', 'RtZYMVvmkE0JE',
     ),
+    (
+        'https://www.youtube.com/s/player/59b252b9/player_ias.vflset/en_US/base.js',
+        'D3XWVpYgwhLLKNK4AGX', 'aZrQ1qWJ5yv5h',
+    ),
 ]