mac: 10.11 SDK compatibility
mac: 10.11 SDK compatibility

This doesn’t really provide compatibility, it just ignores the
deprecation warning for +[NSURLConnection
sendSynchronousRequest:returningResponse:error:].

The suggested replacement, NSURLSession, was new in 10.9, and this code
needs to run on 10.6, so it’s not usable here, at least not without a
runtime check.

BUG=crashpad:65
R=rsesek@chromium.org

Review URL: https://codereview.chromium.org/1395673002 .

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