HHVM compatibility: array sometimes can be Traversable

All checks on instance of Traversable prepended with is_object check.

See facebook/hiphop-php#1034 for details.
merged branch javer/hhvm-array-traversable (PR #1192)

This PR was merged into the master branch.

Discussion
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HHVM compatibility: array sometimes can be Traversable

All checks on instance of Traversable prepended with is_object check.

See facebook/hiphop-php#1034 for details.

Commits
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b1b1e3c HHVM compatibility: array sometimes can be Traversable