Remove comment about issue 368416

Since the issue was opened, the validity of removing
RenderObject::positionFromPaintInvalidationContainer
was questioned and it was determined that it's
probably not such a good idea anyway.

BUG=368416

Review URL: https://codereview.chromium.org/423943002

git-svn-id: svn://svn.chromium.org/blink/trunk@179078 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Oilpan: Move SelectorFilter to oilpan's heap

This CL moves SelectorFilter::ParentStackFrame from a private section to a public section to use a WTF_ALLOW_INIT_WITH_MEM_FUNCTIONS macro.

BUG=340522

Review URL: https://codereview.chromium.org/422143005

git-svn-id: svn://svn.chromium.org/blink/trunk@179079 bbb929c8-8fbe-4397-9dbb-9b2b20218538