Switch to RETURN_IF_EMPTY_HANDLE for empty handle checks.

This makes sure that every place where we assume an empty handle is
indicating a pending exception gets asserted accordingly.

R=machenbach@chromium.org

Review URL: https://codereview.chromium.org/18427003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@15509 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Keep two empty lines between declarations for cpp files

R=yangguo@chromium.org

Review URL: https://codereview.chromium.org/18509003

Patch from Haitao Feng <haitao.feng@intel.com>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@15510 ce2b1a6d-e550-0410-aec6-3dcde31c8c00