Yield array from AC::Parameters#each for block with one arg

[domcleal]

Matches Hash#each behaviour as used in Rails 4.

Other Information

Reproducer: https://gist.github.com/df6296853a73ca3f714174278ec01138 (passes on 4-2-stable, fails on 5-0-stable or master)

Ruby's Hash#each_pair implementation, which also switches on the block arity: https://github.com/ruby/ruby/blob/v2_4_0/hash.c#L1810

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[rafaelfranca]

We can always yield an array since the block will rake care of destructing the array in two argument.

[domcleal]

Ah neat. Thanks, updated and rebased the PR.