moved truffleruby to allow_failures group in travis.yml

[iliabylich]

No description provided.

[eregon]

Sorry about that, I will try to investigate why we run in a fatal OutOfMemoryError here: https://travis-ci.org/github/whitequark/parser/jobs/727303862

[eregon]

For whatever reason it seems I cannot reproduce this in 3 runs: https://travis-ci.org/github/eregon/parser/builds

[iliabylich]

right, it fails randomly, but I've noticed that the error comes on the last step of the test suite where we check that all AST nodes that are created are known for our AST visitor.

Here's the for_each_node method -

parser/test/helper.rb

Line 70 in 7c5558d

def for_each_node(&block)

, there are a few places in tests that call it. Basically, we record all nodes and do a couple of post-checks in the Minitest.after_run {} block.