END blocks trap any exceptions raised in them.

* Begin blocks don't trap them.
[Truffle] Need to transfer because expensive construction of exceptions in Float#to_i.
[Truffle] Remove old benchmark reference data from ignore.
[Truffle] We don't want to pull in all of JRuby's stdlib at the moment.
[Truffle] Start our own stdlib path, delegating to JRuby's.
[Truffle] Import erb and cgi/util.
[Truffle] Bring in ERB specs from RubySL.
[Truffle] Range#begin.
[Truffle] Range#end.
[Truffle] Remove strange lowering on Range#include? - can't see why it's needed - will probably find out.
[Truffle] String#b.
[Truffle] Set up RubySL specs in truffle.mspec.
[Truffle] Add mvn -Ptruffle-specs-rubysl phase.
[Truffle] Add mvn -Ptruffle-specs-rubysl to Travis, but also to allowed failures for now.
[Truffle] Dup String#b.
[Truffle] Implemented KeyError.
[Truffle] Added a shim for Hash#fetch.
[Truffle] The evaluated block takes precedence over the default value in Hash#fetch.
[Truffle] Shim of Thread#[] and #[]=
[Truffle] printf -> sprintf, and then define former in terms of latter in Ruby