This patch changes delete selection process not to insert redundant BR element for merging.

* editing/deleting/delete-br-001.html:
 This patch keeps origin BRs.
* editing/deleting/delete-before-block-image-2-expected.txt
 This patch keeps an origin IMG element rather than inserting new one.
* editing/deleting/delete-br-001.html
  This patch keeps original BR elements rather than removing BR then inserting BR again.
* editing/deleting/delete-br-after-image.html
 This patch adds a new test described in issue report.
* editing/deleting/delete-inline-br.html
 Imported from http://trac.webkit.org/changeset/154479
* editing/inserting/font-size-clears-from-typing-style-expected.txt
 This patch doesn't causes redundant block, DIV, merging.

BUG=173835,235742
R=eseidel@chromium.org

Review URL: https://codereview.chromium.org/18799004

git-svn-id: svn://svn.chromium.org/blink/trunk@157505 bbb929c8-8fbe-4397-9dbb-9b2b20218538