[DebugVisualizers] Remove NGPhysicalLineBoxFragment::Children This member was removed in r873361 crrev.com/c/2830411. This patch removes it accordingly. Change-Id: Ic9f42a93d581c7533aa1cd427384c16f9a0e51dc Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3122704 Reviewed-by: Yoshifumi Inoue <[email protected]> Reviewed-by: Bruce Dawson <[email protected]> Commit-Queue: Koji Ishii <[email protected]> Cr-Commit-Position: refs/heads/main@{#916228} NOKEYCHECK=True GitOrigin-RevId: 741dfd6e18494813e1ae7c83001d1b093c21623f