Revert 156140 "Form control collections should not hold removed ..."

It was not a right fix. It removed a standard-defined behavior.

> Form control collections should not hold removed controls.
> 
> wkrev.com/20260 introduced a Firefox-compatible behavior which did not remove
> form controls from a form control collection if a control is accessed by its
> name. This behavior doesn't conform to the HTML standard and isn't compatible
> with recent IE. We remove this behavior.
> 
> BUG=190026
> 
> Review URL: https://chromiumcodereview.appspot.com/23088009

TBR=tkent@chromium.org

Review URL: https://codereview.chromium.org/23448006

git-svn-id: svn://svn.chromium.org/blink/trunk@156731 bbb929c8-8fbe-4397-9dbb-9b2b20218538