RenderTextWin: Break line on a newline character ('\n')

BUG=248597
R=msw

Review URL: https://codereview.chromium.org/88423005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@237752 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 237752