WebView accessibility key bindings do not allow mapping of all meta keys....

WebView accessibility key bindings do not allow mapping of all meta keys. Exception when turning off acessibility and having a WebView showing content.

bug:3341772

1.  Now a key in the binding is represented as a long with 32 MSB for modifiers and 32 LSB for keyCode.

bug: 3340732

1. Added check in the WebView key handling code to diable the accessibility injector/injected script in
   case accessibility is been disabled after loading the content.

Change-Id: Ic3746dff16ec77ba682a5b139cec0e6afd8fc839