Revert 167807 "Support std::pair in garbage collected collections"

Broke the Win x64 compile.

> Support std::pair in garbage collected collections
> 
> R=ager@chromium.org, haraken@chromium.org, vegorov@chromium.org, wibling@chromium.org, zerny@chromium.org
> BUG=
> 
> Review URL: https://codereview.chromium.org/179653002

TBR=erik.corry@gmail.com

Review URL: https://codereview.chromium.org/176973005

git-svn-id: svn://svn.chromium.org/blink/trunk@167839 bbb929c8-8fbe-4397-9dbb-9b2b20218538