cc: Add support for continuing an iteration after erasing from a QuadList.
EraseAndInvalidateAllPointers() now return a valid Iterator that can be used to
continue the iteration.
ListContainerBase::end() is modified so that it stays valid after insertion or
deletion.
This is needed for https://codereview.chromium.org/
1304053016.
BUG=527222
TEST=ListContainerTest.DeletionWhileIterating
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel
Review URL: https://codereview.chromium.org/
1305343004
Cr-Commit-Position: refs/heads/master@{#347265}