Drop deprecated ScopeBody and ScopeExpression from walker
Drop deprecated ScopeBody and ScopeExpression from walker

Issue #656

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