Removed deprecated functions from v8's external API.

Removed the following deprecated functions:

   * Object::GetPointerFromInternalField
   * Object::SetPointerInInternalField
   * External::Wrap
   * External::Unwrap
   * Context::GetData
   * Context::SetData

They have been deprecated in the 3.15 branch and are not used by Chrome anymore.
Furthermore, judging from bug reports and email threads, embedders like node.js
and others are already using 3.15, too. All removed API entries can be emulated
by a one-liner, so adapting should not be hard for anybody.

We want to introduce more deprecations soon, but to keep things simple and avoid
having old and not-so-old deprecations in v8.h, the 3.15 deprecations are now
removed.

In general, the strategy of keeping deprecated things for one stable release and
then removing them seems to be a good compromise between a maintenance nightmare
and annoying external embedders. :-)

Review URL: https://codereview.chromium.org/11885019

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@13372 ce2b1a6d-e550-0410-aec6-3dcde31c8c00