Remove line break when it is collapsed while pasting in contenteditable

While pasting on a line break inside a contenteditable div, the line
break(the br tag) stays in the node but while typing it gets removed.
This change will remove the line break from the contenteditable while
pasting content.

Following tests expectations were updated as they were expecting
redundant br tag after some command is performed in a node the tests
below are under third_party/blink/web_tests/

editing/execCommand/remove-list-item-1.html
external/wpt/editing/data/insert-list-items-in-table-cells.js
external/wpt/editing/data/inserthtml.js

editing/deleting/5206311-2-expected.txt
editing/deleting/merge-list-items-in-same-list-expected.txt
editing/pasteboard/5078739-expected.txt
editing/pasteboard/display-block-on-spans-expected.txt
editing/pasteboard/do-not-copy-unnecessary-styles-expected.txt
editing/pasteboard/paste-blockquote-into-blockquote-3-expected.txt
editing/pasteboard/paste-text-with-style-2-expected.txt
editing/pasteboard/paste-text-with-style-3-expected.txt
editing/pasteboard/paste-text-with-style-4-expected.txt
editing/pasteboard/paste-text-with-style-5-expected.txt
editing/pasteboard/preserve-underline-color-expected.txt
external/wpt/editing/run/delete_4001-5000-expected.txt
external/wpt/editing/run/forwarddelete_4001-5000-expected.txt
external/wpt/editing/run/insertimage-expected.txt
external/wpt/editing/run/insertlinebreak-expected.txt
external/wpt/editing/run/insertparagraph_1001-2000-expected.txt
external/wpt/editing/run/insertunorderedlist_1001-2000-expected.txt
external/wpt/editing/run/outdent_2001-last-expected.txt
fast/lists/remove-listmarker-and-make-anonblock-empty-expected.txt
platform/win/editing/pasteboard/display-block-on-spans-expected.txt

Following tests expectations were updated since they were correctly
expecting fails on the current baseline, after this change these tests
will now start to pass third_party/blink/web_tests/
external/wpt/editing/run/delete_1-1000-expected.txt
external/wpt/editing/run/delete_4001-5000-expected.txt
external/wpt/editing/run/delete_5001-6000-expected.txt
external/wpt/editing/run/forwarddelete_1-1000-expected.txt
external/wpt/editing/run/forwarddelete_1001-2000-expected.txt
external/wpt/editing/run/forwarddelete_4001-5000-expected.txt
external/wpt/editing/run/forwarddelete_5001-6000-expected.txt
external/wpt/editing/run/inserthtml-expected.txt
external/wpt/editing/run/insertimage-expected.txt
external/wpt/editing/run/insertorderedlist_1-1000-expected.txt
external/wpt/editing/run/insertorderedlist_1001-last-expected.txt
external/wpt/editing/run/insertunorderedlist_1-1000-expected.txt
external/wpt/editing/run/outdent_1001-2000-expected.txt
external/wpt/editing/run/outdent_2001-last-expected.txt
platform/mac/external/wpt/editing/run/delete_1001-2000-expected.txt
platform/win/external/wpt/editing/run/delete_1001-2000-expected.txt

Bug: 40805258
Change-Id: I0d9017637c75809ee86f57969b0f1c5b423d7315
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5764545


Reviewed-by: Kent Tamura <tkent@chromium.org>
Commit-Queue: Utkarsh Pathak <utpathak@microsoft.com>
Reviewed-by: Siye Liu <siliu@microsoft.com>
Cr-Commit-Position: refs/heads/main@{#1349545}