Update nss_revision to r275286.

DEPS

 # This file is automatically processed to create .DEPS.git which is the file
 # that gclient uses under git.
 #
 # See http://code.google.com/p/chromium/wiki/UsingGit
 #
 # To test manually, run:
 #   python tools/deps2git/deps2git.py -o .DEPS.git -w <gclientdir>
 # where <gcliendir> is the absolute path to the directory containing the
 # .gclient file (the parent of "src").
 #
@@ skipping 38 matching lines @@
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling Skia
   # and V8 without interference from each other.
   "v8_branch": "trunk",
   "v8_revision": "21682",
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling WebRTC
   # and V8 without interference from each other.
   "webrtc_revision": "6346",
   "jsoncpp_revision": "248",
-  "nss_revision": "271760",
+  "nss_revision": "275286",
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling swarming_client
   # and whatever else without interference from each other.
   "swarming_revision": "ae8085b09e6162b4ec869e430d7d09c16b32b433",
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling openssl
   # and whatever else without interference from each other.
   "openssl_revision": "271781",
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling ANGLE
@@ skipping 714 matching lines @@
                 "-s", "src/third_party/drmemory/drmemory-windows-sfx.exe.sha1",
               ],
   },
   {
     # A change to a .gyp, .gypi, or to GYP itself should run the generator.
     "name": "gyp",
     "pattern": ".",
     "action": ["python", "src/build/gyp_chromium"],
   },
 ]