Reland "Use symbols instead of hidden properties for i18n markers."

R=dslomov@chromium.org

Review URL: https://codereview.chromium.org/618213002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24362 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
Fix test-spaces on win64

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

Review URL: https://codereview.chromium.org/615423002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24363 ce2b1a6d-e550-0410-aec6-3dcde31c8c00