Try to work around Travis failure on Node 0.12
Try to work around Travis failure on Node 0.12

ternjs/acorn,TimothyGu/acorn,marijnh/acorn,mysticatea/acorn,marijnh/acorn,TimothyGu/acorn,marijnh/acorn,mysticatea/acorn,TimothyGu/acorn,ternjs/acorn,ternjs/acorn,mysticatea/acorn