A64: fix cctest/test-code-stubs-a64/ConvertDToI.

R=danno@google.com

Review URL: https://codereview.chromium.org/169863002

Patch from Ulan Degenbaev <ulan@chromium.org>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@19420 ce2b1a6d-e550-0410-aec6-3dcde31c8c00