When an Array subclass is used as the receiver for concat, or with
certain usages of @@species, the output that's constructed is of
a different type with new slow path logic. This slow path still
made references to elements, so it's important that bounds checking
for a too-long result still be done. This patch repairs that bounds
checking.

R=cbruni
LOG=Y
BUG=chromium:592340

Review URL: https://codereview.chromium.org/1782443002

Cr-Commit-Position: refs/heads/master@{#34636}