Fix for 350887: CHECK failure on new_length->IsSmi()

Fix for 350887: CHECK failure on new_length->IsSmi()

In ElementsAccessorBase::SetLengthImpl for a dictionary array, we try to
optimize setting array length if the new length is a smi. However, we
refuse to set an array length to less than the index of the highest
non-configurable array element. This index may be outside of smi range.

Handle this case accordingly.

BUG=350887
LOG=N
R=dslomov@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=19787

[Dmitry Lomov (no reviews), 2014-03-11 10:26:45]

lgtm

[mvstanton, 2014-03-11 10:30:18]

Committed patchset #1 manually as r19787 (presubmit successful).