DockBatteryMeter: Avoid double detach when view is rebuilt

If the view is reconstructed for some reason (like applying a theme)
on a device without a dock battery, it'll try to detach and unregister
twice. The second unregister will case an NPE since the first one
killed the listener. Fixit.

Change-Id: Idcc0c7c87ef205ddc085a9e036fe630afd9d7012
Merge "DockBatteryMeter: Avoid double detach when view is rebuilt" into cm-11.0
Allow using Classic WebView

Squashed commit of the following:

commit 1e64fc6008a5d00ef6a72b2a6f443019b261996a
Author: Chirayu Desai <cdesai@cyanogenmod.org>
Date:   Tue Nov 12 18:53:53 2013 +0530

    WebViewFactory: Re-add support for switching WebView.

    Change-Id: I6a4a62d64014a49e7bdf1bff3581aab79b680f15

commit 069b610aa0446eb4181b73484ce9619221c7d36a
Author: Chirayu Desai <cdesai@cyanogenmod.org>
Date:   Tue Nov 12 18:41:43 2013 +0530

    Revert "Delete the old WebView."

    This reverts commit 94c0057d67c2e0a4b88a4f735388639210260d0e.

commit 4f6f46a12f5c63100cbe7a582aff07a0529f1483
Author: Chirayu Desai <cdesai@cyanogenmod.org>
Date:   Tue Nov 12 18:41:39 2013 +0530

    Revert "Restore 4 classes that were accidentally deleted"

    This reverts commit 328dd7d7059c70b6776c6e29f9ea315f2f8aed3f.

Change-Id: Iba847a04b515cada0eb32cc86026b60469108d80