swift234

Revert "XFAIL failing IDE tests while BenL investigates. rdar://20245658."

This reverts commits r26369 & r26381.
After upstream clang changes, reverted r25843 which was compensating for a previous upstream clang change.

But keep test/IDE/complete_from_clang_framework.swift disabled for further investigation, because it
seems to have some duplications in a code-completion test.

rdar://20245658&20247922

Swift SVN r26430