Revert 159726 "Move strings and collection class buffers into th..."

> Move strings and collection class buffers into the WTF buffer partition.
> 
> This patch also removes two static initializers / destructors.
> Blink coding style is to generally avoid these by having a static pointer to the
> non-POD type, initializing it with an inline if, and letting it leak. However,
> there are a few instances where that style is violated and these are causing
> trouble by illegally touching Blink objects after WebKit::shutdown has been
> called.
> 
> Easy to fix: two sites switched to standard style.
> 
> BUG=270531
> 
> Review URL: https://codereview.chromium.org/25644002

TBR=cevans@chromium.org

Review URL: https://codereview.chromium.org/27555002

git-svn-id: svn://svn.chromium.org/blink/trunk@159798 bbb929c8-8fbe-4397-9dbb-9b2b20218538