For V8, only build d8 on target

BUG=none
TBR=machenbach@chromium.org
LOG=n

Review URL: https://codereview.chromium.org/139403002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@18619 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Revert "Make it possible to compile d8 for the host toolset as well" and "For V8, only build d8 on target"

This reverts commits r18618 and r18619 for breaking arm compilation.

BUG=
TBR=jochen@chromium.org

Review URL: https://codereview.chromium.org/139273004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@18620 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Merge remote-tracking branch 'upstream/bleeding_edge' into bleeding_edge