Fix bug in HHBBC's RemoveUnusedLocals

Summary: It was missing a range check.

Reviewed By: @jdelong
Skip arbitrary number of 0xff padding bytes in JPEG

Summary: There's no reason to limit the number of 0xff padding bytes while trying
to parse JPEG. Let's remove the arbitrary limit of 26 and keep reading
the file and skipping them.

Reviewed By: @billf

Differential Revision: D1650960
Port WarmupRequestHandler fixes to rc branch

Reviewed By: @markw65

Differential Revision: D1664573
Use Func::destroy to clean up elements of the pseudomain cache

Summary: Funcs in the pseudomain cache are allocated by clone -- it seems like
they should be deallocated by destroy, rather than just deleted.  (ASAN
complains about the mismatch between malloc'ing the Func and deleting it.)

Reviewed By: @markw65

Differential Revision: D1668805

Signature: t1:1668805:1415417063:efd7495176f15d82660cd10037d5a0d54b52588c
Deep initialization for constant properties

Summary: Defined constants may be ref-counted (e.g. resources) and require deep
initialization when used to initialize instance properties.

Fixes #4111

Reviewed By: @fredemmott

Differential Revision: D1658088

Signature: t1:1658088:1415137574:011205e3e604bb711437149f2ef1ed3b3be830b5
Improve fix for issue #4111

Summary: Closes https://github.com/facebook/hhvm/pull/4180

Reviewed By: @JoelMarcey

Differential Revision: D1669151

Signature: t1:1669151:1415548684:b89950d6e0f02fa8a4fc4bc0a9b17d4fb5835a07
Fixed xpath's php:functionString

Summary: Added CallerFrame before dom_xpath_ext_function_php's call to xmlXPathEvalExpression in case libxml2 needs to call back into HHVM.
The xpath query might contain ```php:functionString``` which triggers a call to any arbitrary php function.

Also fixed a bug where the arguments in an xpath php:functionString were reversed. For example, if the xpath was ```/foo[php:functionString('preg_match', '{$regex}',@​bar)]```, preg_match was being called as ```preg_match($bar, $regex)``` instead of ```preg_match($regex, $bar)```.

Closes https://github.com/facebook/hhvm/pull/4120

Reviewed By: @sgolemon

Differential Revision: D1656106

Signature: t1:1656106:1415132682:3423279074575c41ba3f39136ab2abd3f29ae232
Fix closure var_export

Summary: Just export the name of the class to avoid infinite recursion.

Fixes #4176

Reviewed By: @fredemmott

Differential Revision: D1668260

Signature: t1:1668260:1415405711:bc1f17b7b39fc980cdff4ae8a4637fcdee085784