Add/remove spell checking markers in text inputs depending on focus.

Inputs are spell checked by default. However since it's very
likely user names, cities, addresses and other stuff that
possibly isn't in the dictionary will be put into them when
unfocused misspelling markers are removed from them (so
they are not all red all the time). However they are
added again on input re-focusing.

BUG=168029

Review URL: https://chromiumcodereview.appspot.com/21024004

git-svn-id: svn://svn.chromium.org/blink/trunk@155420 bbb929c8-8fbe-4397-9dbb-9b2b20218538