Introduce intrinsics for double values in Javascript.

R=svenpanne@chromium.org

Review URL: https://codereview.chromium.org/178583006

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@19704 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
A64: Tidy up some TODOs in GenerateRecordCallTarget.

R=jochen@chromium.org

Review URL: https://codereview.chromium.org/184433002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@19705 ce2b1a6d-e550-0410-aec6-3dcde31c8c00