[LayoutNG] Handle forced OOF break in SimplifiedOOFLayoutAlgorithm

As a result of CL:2554568, we may add a forced break to an OOF.
However, if we later add a break token to the fragmentainer
associated with that incoming OOF break token as a result of OOF
fragmentation, we will fail to add the rest of the children to the
replaced fragmentainer. Skip over such break tokens to address this.

Bug: 1305726
Change-Id: I1ffaa962c33e929f31f92d8691dce1bb9fda26ba
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3523183
Reviewed-by: Morten Stenshorne <mstensho@chromium.org>
Commit-Queue: Alison Maher <almaher@microsoft.com>
Cr-Commit-Position: refs/heads/main@{#980781}