Merging r368058:

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r368058 | sureyeaah | 2019-08-06 19:01:12 +0200 (Tue, 06 Aug 2019) | 11 lines

Fixed toHalfOpenFileRange assertion fail

Summary:
- Added new function that gets Expansion range with both ends in the same file.
- Fixes the crash at https://github.com/clangd/clangd/issues/113

Subscribers: ilya-biryukov, jkorous, arphaman, kadircet, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D65754
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llvm-svn: 368407