Fixing bugs 3315632 3235958, performing a clean up of the WebView...

Fixing bugs 3315632 3235958, performing a clean up of the WebView accessibility feature. Updated event hadndling to deliver all key events to javaScript if a screen reader is injected since the latter is responsible for the full set of navigation and exploration actions.

Change-Id: Id1639828559161e0850dee04baa0a7afb2576ea8