Reimplement argument passing without using debug_backtrace()
Use ReflectionParameter::getTypehintText() if available
Fix testCanOverrideExpectedParametersOfInternalPHPClassesToPreserveRefs
Replaced foreach() + key() with for($i = 0...

Not sure why key() worked in the first place, it definitely doesn't
generally, and the code was flakey.
Merge pull request #246 from fredemmott/hhvm

Increase HHVM compatibility