Fix a missing SpillStack

LdClsPropAddr can throw if it doesn't have a target.
Initial support for inlining small functions

Sets up the translator analyze pass to create a Tracelet for
the callee at every statically-known FCall.  If the callee has an
appropriate shape (in this diff, it must be a function consisting of
"return $this->foo" for a declared property), we can inline it in
HHIR.  Restructures the IR relating to frames some so we can eliminate
the stores relating to ActRec in this simple case (see the comments in
dce.cpp and hhbctranslator.cpp for details).  Includes partial support
for inlining callees with locals, but it's disabled for now because
they will keep the frame live.
Add SpillStack's sources to the instruction type assertions @override-unit-failures

Check the types on its sources.
Implement PHP 5.4's short array syntax

We have traits and some other PHP 5.4'isms why not the short array syntax as well?