This commit adds a CHECK that verifies that the file event watcher is
not started twice, which would be indicative of a bug in lib/fs.js.

PR-URL: nodejs#7374
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>

Remove TLSWrap::write_queue_size_, it's not used anywhere.

PR-URL: nodejs#7374
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>

The code assigned the result of EVP_get_digestbyname() to data members
called md_ that were not used outside the initialization functions.

PR-URL: nodejs#7374
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>

PR-URL: nodejs#7374
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>

PR-URL: nodejs#7374
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>

Pointed out by Coverity.  Introduced in commit 5b8e1da from September
2011 ("Initial pass at zlib bindings".)

The asynchronous version of Write() used a pointer to a stack-allocated
buffer on flush.  A mitigating factor is that zlib does not dereference
the pointer for zero-sized writes but it's still technically UB.

PR-URL: nodejs#7374
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>

Pointed out by Coverity.  Introduced in commits 3546383 ("process_wrap:
avoid leaking memory when throwing due to invalid arguments") and
fa4eb47 ("bindings: add spawn_sync bindings").

The return statements inside the if blocks were dead code because their
guard conditions always evaluated to false.  Remove them.

PR-URL: nodejs#7374
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>