Drop invalid assumption from TastyUnpickler

[Jentsch]

Fixes #22265

I'm actually not sure if the scaladox-testcases sub-project is the right place for the test. In sbt scaladoc/test fails the dotty.tools.scaladoc.tasty.comments.MemberLookupTests.

[jchyb]

Hi @Jentsch. Thank you for submitting the fix. I will admit I'm a little uncomfortable with just removing the assertion in Tasty Unpickler. It does seem like the compiler pickles incorrect stuff to begin with. Running scalac -print-tasty breaks.tasty reveals that there is a recorded source change on the inlined IMPORT node (which does not really make sense, as it should be on the outer BLOCK node):

    92:               BLOCK(11) // source change, in my opinion, should be recorded here
    94:                 UNITconst
    95:                 IMPORT(8) // source change was recorded here
    97:                   TERMREF 24 [List]
    99:                     TERMREF 25 [package]
   101:                       SHAREDtype 56
   103:                   IMPORTED 26 [empty]

I'll try to take a closer look into this in the coming days