AI 143733: Fix for issue 1648553: IME overlaps over focus ring in gmail search...

AI 143733: Fix for issue 1648553: IME overlaps over focus ring in gmail search box.  In WebView::requestChildRectangleOnScreen we now move a rectangle up if its bottom is offscreen, even if its top is not.  We also move it so that its top is at the top third of the WebView's height (if it still fits on screen) so that you can see space (and potentially other input fields) below it.
  BUG=1648553

Automated import of CL 143733