[Extensions] Add support for persistent callback listener

This is going to be the base of the EventTarget implementation. It is
important to remove the listener at some point otherwise the object will
leak.
[Extensions] Add browsertests for the persistent callback listener

The test implements a heartbeat which works in a similar way of an EventTarget.
The callback is set only one and gets called multiple times.
[Extensions] Remove development debug statements

These debugging statements were useful during development, but now
as we are feeling confident that everything should be working, they
can be removed.
[Android] Disable the unit test for DeviceCapabilities.

It's failed in both shared and embedded modes. Need to fix them.
Create one issue to track it:
https://crosswalk-project.org/jira/browse/XWALK-102
Merge pull request #1045 from yongsheng/master

[Android] Disable the unit test for DeviceCapabilities.
Merge pull request #1039 from vcgomes/remove-development-debugs

[Extensions] Remove development debug statements
Merge pull request #1038 from tmpsantos/persistent_callback

[Extensions] Support for persistent callback
[WiDi API] Implement navigator.presentation.requestShow API on Android

This patch is to implement navigator.presentation.requestShow for
showing a new HTML page on the secondary display.

IMPLEMENTATION NOTES:
o Web messaging can be used for communication between the opener window
  and presentation window.
o Only one presentation is allowed to be created. If there is already a
  presentation showing, an attempt to call requestShow will fail.
o A presentation will be dismissed in case of:
  1. window.close is called to close the presentation DOM window, or
  2. The presentation display is disconnected, and there is no available
     display for presentation show any more.
o The DOM window object for presentation is retrieved from the routing id
  of RenderView. It follows the way chrome.app.window.create does.

TODOS:
o Add `destroy` into XWalkView to destroy an XWalkView instance.
o Add `Promise` support for requestShow API instead of using callback.
o Make it backward-compatible on Android

SPEC=http://otcshare.github.io/presentation-spec/index.html
BUG=https://github.com/crosswalk-project/crosswalk/issues/577