Implemented SoapHeader properties

Summary: SoapHeader has public facing properties that can be manipulated. Those properties are undocumented.

Fixes #2822

Reviewed By: @fredemmott

Differential Revision: D1360488
Punt if framep is constant

Summary: Band-aid to prevent crashing; we still need to find out why
we're generating bogus IR.

Reviewed By: @markw65

Differential Revision: D1366150
Implement __toString() for reflection classes

Summary: ReflectionFunction
ReflectionMethod
ReflectionClass
ReflectionObject
ReflectionProperty
ReflectionParameter

Also...
* Found/fixed a crash in ReflectionClass::getOrderedConstants()
* Added missing function ReflectionClass::isIterable()

Closes #1571

Reviewed By: @fredemmott

Differential Revision: D1363317
Embed hhi files into hh_server binary

Summary: This will remove an annoying install step when getting started
with Hack.

Reviewed By: @elgenie

Differential Revision: D1353049
Read hhconfig to determine if we should use embedded hhi's

Summary: This is separate from D1353049 so that it can be separately
reverted. We need a transition plan for FB www, and this is simple. This
isn't such a huge deal for open-source users -- they can just delete
their hhi directories as part of their hh_server upgrade. For more
involved upgrades, we plan to go this path, except actually go an entire
OSS release with the config option present, and all sorts of automatic
upgrade stuff, but we don't have the machinery for that quite yet.

Reviewed By: @elgenie

Differential Revision: D1364920
Make hhi file valid

Summary: This should have been decl in the first place.

Reviewed By: @elgenie

Differential Revision: D1364934
fix a memory leak in simplexml

Summary: Oops, this one's on me. Since t_getiterator passes control over from the
sxe object to the iterator, we need to actually release sxe when our
iterator's destructor is called.

Fixes #2854.
Closes #2859

Reviewed By: @sgolemon

Differential Revision: D1366174

Pulled By: @JoelMarcey
Infer that IncDecL of an Int goes to Int in no-float-overflow mode

Reviewed By: @jdelong

Differential Revision: D1364180
Silence notice when fetching unset property via reflection

Summary: PHP5 doesn't throw an unset notice when we attempt
to fetch an unset value from a reflected object, so we shouldn't.

Closes #2013

Reviewed By: @JoelMarcey

Differential Revision: D1364543
Fix some arm bugs exposed by the tracelet region selector

Summary: I'm not sure why these weren't happening with analyze, but they're
real issues:
- When I did my vmfp/sp/pc refactor I missed a few accessors that need to be
  the unsafe versions.
- ARM::BackEnd::emitFwdJmp was unimplemented, and it's needed by the main
  codegen loop to link blocks together sometimes.

Reviewed By: @oyamauchi

Differential Revision: D1365090
Increase write lease's kStandardHintExpireInterval to 1500

Summary: I noticed some bad interleaving of translations in the TC that
suggested the write lease was expiring too soon.  So I experimented
with different values and tuned it.

Reviewed By: @swtaarrs

Differential Revision: D1365796
Add JIT support for Unbox bytecode instruction

Summary: I noticed we were always InterpOne'ing this instruction, and HHBBC
seems to have caused it to be generated more often (for cases it can
prove the result of a function is always boxed), resulting in bytecode
sequences like: FCallD ; BoxRNop ; Unbox

Reviewed By: @swtaarrs

Differential Revision: D1365851