[anchor-position] Fix an error in `anchor-position-writing-modes-002.html`

This patch removes an excessive `<style>` open tag in the test.

Bug: 1382524
Change-Id: Ie43b77a635b320f0ba1bc9166fe3a3660b995c29
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4060949


Auto-Submit: Koji Ishii <kojii@chromium.org>
Commit-Queue: Kent Tamura <tkent@chromium.org>
Reviewed-by: Kent Tamura <tkent@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1076463}