Instantiating a Buffer of length zero would set the kNoZeroFill flag to
true but never actually call ArrayBuffer::Allocator(). Which means the
flag was never set back to false. The result was that the next
allocation would unconditionally not be zero filled.

Add test to ensure Uint8Array's are zero-filled after creating a Buffer
of length zero. This test may falsely succeed, but will not falsely fail.

Fix: #2930
PR-URL: #2931
Reviewed-By: Rod Vagg <rod@vagg.org>

Notable changes

* buffer: Fixed a bug introduced in v4.1.0 where allocating a new
  zero-length buffer can result in the next allocation of a TypedArray
  in JavaScript not being zero-filled. In certain circumstances this
  could result in data leakage via reuse of memory space in
  TypedArrays, breaking the normally safe assumption that TypedArrays
  should be always zero-filled. (Trevor Norris) #2931.
* http: Guard against response-splitting of HTTP trailing headers
  added via response.addTrailers() by removing new-line ([\r\n])
  characters from values. Note that standard header values are already
  stripped of new-line characters. The expected security impact is low
  because trailing headers are rarely used. (Ben Noordhuis) #2945.
* npm: Upgrade to npm 2.14.4 from 2.14.3, see release notes for full
  details (Kat Marchán) #2958
  - Upgrades graceful-fs on multiple dependencies to no longer rely on
    monkey-patching fs
  - Fix npm link for pre-release / RC builds of Node
* v8: Update post-mortem metadata to allow post-mortem debugging tools
  to find and inspect:
  - JavaScript objects that use dictionary properties
    (Julien Gilli) #2959
  - ScopeInfo and thus closures (Julien Gilli) #2974

Notable changes

* buffer: Fixed a bug introduced in v4.1.0 where allocating a new
  zero-length buffer can result in the next allocation of a TypedArray
  in JavaScript not being zero-filled. In certain circumstances this
  could result in data leakage via reuse of memory space in
  TypedArrays, breaking the normally safe assumption that TypedArrays
  should be always zero-filled. (Trevor Norris) #2931.
* http: Guard against response-splitting of HTTP trailing headers
  added via response.addTrailers() by removing new-line ([\r\n])
  characters from values. Note that standard header values are already
  stripped of new-line characters. The expected security impact is low
  because trailing headers are rarely used. (Ben Noordhuis) #2945.
* npm: Upgrade to npm 2.14.4 from 2.14.3, see release notes for full
  details (Kat Marchán) #2958
  - Upgrades graceful-fs on multiple dependencies to no longer rely on
    monkey-patching fs
  - Fix npm link for pre-release / RC builds of Node
* v8: Update post-mortem metadata to allow post-mortem debugging tools
  to find and inspect:
  - JavaScript objects that use dictionary properties
    (Julien Gilli) #2959
  - ScopeInfo and thus closures (Julien Gilli) #2974

PR-URL: #2995