[Truffle] - Fixing tests broken by Truffle warn message.

Truffle is showing a warn message when running on JDK8. This is a dirty
hack that checks if the JDK version 8 and if it's then expects the
truffle warn instead of an empty string.
[Issue-1556] - Dir.home should first try to return the path defined in HOME.

Dir.home should point to the path defined in HOME and if it's nil then
it should point to path defined user.home and if both are nil then
should point to the path defined in LOGDIR.
Merge pull request #1560 from jruby/fixing-ci

Fixing test that was broken by the warns message throwed by Truffle
[Truffle] Improve module parents and constant lookup.
[Truffle] Remove optional replace in read constant node.
[Truffle] Support calling super with no arguments.
[Truffle] Get all __FILE__ specs working.
[Truffle] Tidy up.
[Truffle] Passing most alias specs.
[Truffle] More class specs passing.
[Truffle] More singleton specs passing.
[Truffle] RubyMethod should never be visible to users.
[Truffle] Undef specs all passing.
[IR] Deleted some stale commented out code.
[IR] Fix longstanding bug setting up splats in call args.

* Discovered ArgumentError failures in MRI test runs -- found out
  that CallBase was unsplatting a splat which shouldn't have been.
  Try "p [*1..2], 3" before/after.

* This patch fixes it and as a bonus, cleans out an ugly hack that
  was present in buildCallArgs in IRBuilder.

* In the process renamed 'containsSplat' in CallBase to
  'containsArgSplat' -- check if there is a splat in the arg list
  that should be unsplatted while setting up call args.

* 2 more MRI tests now green.
[Truffle] Passing all private specs.
[Truffle] Passing all line specs.
[Truffle] Pass all redo specs.
[Truffle] All retry specs passing.
[Truffle] All precedence specs passing.