add isClosure to ReflectionFunction
Remove a comment in asm-x64.h
Start of a PreClass/Class comment
Always set the dumpable flag for the process
Dont use a local StringData for invoke

If the StringData ever gets put into a String or Variant
it will cause the (stack) memory to be put on the GarbageList,
leading to crashes later. This was exacerbated by not incReffing
the StringData (so the String/Variant didnt even have to outlive
the StringData for this to be a problem).

We probably couldnt hit this case prior to function autoloading,
but now its easy. Making an rpc request to a non-existent function
hits it reliably.

It turns out that invoke is normally entered via the version that takes
a CStrRef, so this should actually be an improvement on the old code
(which threw away the incoming StringData and created a new one on the stack).
Dont flush the targetcache within a request

rpc requests preserve state across requests, so we cant drop
the TargetCache just because the thread has been idle for a
few seconds. The result was that all classes, functions and
certain items of global state became "unloaded" while most
global state was preserved. The autoloader then did its best
to set things straight, but some things were beyond repair.
Introduce SSARange (using folly::Range) in HHIR code.

Slices and Ranges are a handy way to work with arrays and
sub-arrays, and work with C++11 foreach syntax.  Use it in
various places.
Short term fix for GuardType with dce'd dest

Trying to debug sandboxes and I hit this.  I think this fix
is actually correct, although it'd probably be better to teach the
register allocator to require that GuardType is the last use of its
source, and just always map the src value register as the destination.