Add a nbsp at the the end of the text when the next text has a leading space.
This is a regression caused by https://codereview.chromium.org/2175163004.
The above CL adds a plain space between text nodes, but a nbsp should be added
if the next text node has a leading plain space. If not, two spaces are
collapsed into one plain space.
BUG=657631
TEST=editing/inserting/insert-space.html
Review-Url: https://chromiumcodereview.appspot.com/2432083003
Cr-Commit-Position: refs/heads/master@{#426420}
2 files changed
