I've fixed the problems you pointed out, please take another look.
Sasha


The ability to read registers is needed to use Frame Filter API to
display the frames created by JIT compilers.

gdb/Changelog
2014-08-26  Sasha Smundak  <asmundak@google.com>

* python/py-frame.c (frapy_read_register): New function.

2014-08-26  Sasha Smundak  <asmundak@google.com>

* python.texi (Frames in Python): Add read_register description.

2014-08-26  Sasha Smundak  <asmundak@google.com>

* gdb.python/py-frame.exp: Test Frame.read_register.