Fix Array::New(length) in the API to return an array with the provided length.

Fix Array::New(length) in the API to return an array with the provided length.

The internal factory method initializes the elements but does not set
the length property of the array.

Add array api test case for length.

R=antonm@chromium.org
BUG=v8:1256
TEST=cctest/test-api/Array

Review URL: http://codereview.chromium.org/6674034

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@7210 ce2b1a6d-e550-0410-aec6-3dcde31c8c00