Revert 160036 "Don't dispatch blur/focus events if the element's..."

I think this CL is causing "XP Tests (1)" bot to be flaky on BrowserFocusTest.FocusTraversal tests.

> Don't dispatch blur/focus events if the element's page is not focused.
>
> When the page loses focus a blur event is dispatched once, prevent a second dispatch (via e.g. programmatic blur()-ing), when a page doesn't have focus, prevent a focus event dispatch (via e.g. programmatic focus()-ing), as it will receive a focus event when the page regains focus.
>
> R=tkent@chromium.org
> BUG=276757
>
> Review URL: https://codereview.chromium.org/26149002

TBR=lstoakes@gmail.com

Review URL: https://codereview.chromium.org/33353007

git-svn-id: svn://svn.chromium.org/blink/trunk@160140 bbb929c8-8fbe-4397-9dbb-9b2b20218538