Tooling: Ignore file names in tooling::deduplicate.

This was horribly broken due to how the sort predicate works. We would
report a conflict for files with a replacement in the same position but
different names if the length differed. Just ignore paths as this is often
what the user wants. Files can occur with different names (due to symlinks
or relative paths) and we don't ever want to do the same edit in one file
twice.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@217439 91177308-0d34-0410-b5e6-96231b3b80d8
clang-format: [JS] Support regex literals with trailing escaped slash.

Before:
  var regex = / a\//; int i;

After:
  var regex = /a\//;
  int i;

This required pushing the Lexer into its wrapper class and generating a
new one in this specific case. Otherwise, the sequence get lexed as a
//-comment. This is hacky, but I don't know a better way (short of
supporting regex literals in the Lexer).

Pushing the Lexer down seems to make all the call sites simpler.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@217444 91177308-0d34-0410-b5e6-96231b3b80d8