Add regression test for optimized count operation.

This is a regression test for a bug with handling of count operations
that target a JavaScript accessor on the prototype chain in Crankshaft.

R=jkummerow@chromium.org
BUG=chromium:306851
TEST=mjsunit/regress/regress-crbug-306851

Review URL: https://codereview.chromium.org/27702002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@17254 ce2b1a6d-e550-0410-aec6-3dcde31c8c00