Add a getter for the address and size of the code range to the pulic API

Since the x64 backend currently doesn't emit ABI compliant code, it is
not possible to unwind the stack. During Win64 SEH this will cause the
exception handling to abort, and not even call the unhandled exception
handler. Embedders are advised to install a custom unwind callback using
RtlInstallFunctionTableCallback for the entire code range to catch
unwind attempts for exception handling.

BUG=v8:3598
R=svenpanne@chromium.org
LOG=y

Review URL: https://codereview.chromium.org/612043002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24283 ce2b1a6d-e550-0410-aec6-3dcde31c8c00