Missing type cell on ia32 from bindings.

Javascript constructors called from C++ code didn't have a type cell
properly filled in on ia32. This showed up as a bug in webkit bindings.
Re-enabled flag optimize-constructed-arrays.

BUG=
R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/15870002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@14775 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Add asserts to String::GetFlatContent.

R=verwaest@chromium.org
BUG=

Review URL: https://chromiumcodereview.appspot.com/13841012

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@14776 ce2b1a6d-e550-0410-aec6-3dcde31c8c00