.jshintrc

util: implement `writelines()` on atomictempfile

With typehints on the vfs objects, pytype will flag this:

    FAILED: /mnt/c/Users/Matt/hg/.pytype/pyi/mercurial/patch.pyi
    /usr/bin/python3.8 -m pytype.single
        --imports_info /mnt/c/Users/Matt/hg/.pytype/imports/mercurial.patch.imports
        --module-name mercurial.patch -V 3.7
        -o /mnt/c/Users/Matt/hg/.pytype/pyi/mercurial/patch.pyi
        --analyze-annotated --nofail --quick
        /mnt/c/Users/Matt/hg/mercurial/patch.py
    File "/mnt/c/Users/Matt/hg/mercurial/patch.py", line 535, in writerej:
        No attribute 'writelines' on mercurial.util.atomictempfile [attribute-error]
      In Union[
          mercurial.util.atomictempfile,
          mercurial.vfs.checkambigatclosing,
          mercurial.vfs.delayclosedfile,
          mercurial.windows.fdproxy,
          mercurial.windows.mixedfilemodewrapper
      ]

It's not a real problem there (atomictempfile is only created by passing
different args), but it's reasonable for this to implement the function and
behave like a normal file.  There are other functions missing that can be added
if/when needed.

{
    // Enforcing
    "eqeqeq"        : true,     // true: Require triple equals (===) for comparison
    "forin"         : true,     // true: Require filtering for..in loops with obj.hasOwnProperty()
    "freeze"        : true,     // true: prohibits overwriting prototypes of native objects such as Array, Date etc.
    "nonbsp"        : true,     // true: Prohibit "non-breaking whitespace" characters.
    "undef"         : true,     // true: Require all non-global variables to be declared (prevents global leaks)

    // Environments
    "browser"       : true      // Web Browser (window, document, etc)
}