Breakout from http://crrev.com/2380933004 -- there is a desire to rename LayoutObject::container() and LayoutObject::containingBlock(), and potentially other containerFoo()/containingBar() methods, for clarity.

For background see the comment in Source/core/layout/README.md regarding the difference between container() and containingBlock().

These are heavily referenced methods, and we may want to rename associated comments and local vars, so having its own tracking bug seems warranted.