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

Revert "Remove old WebView classes from zygote preload list."

This reverts commit 6067d1a3c7033f6714a60ac02a6b08d6568fe217.

Change-Id: Iba847a04b515cada0eb32cc86026b60469108d80
WebViewClassic: Add freeMemoryForTests

Since the 4.4.3 merge, an override of freeMemoryForTests is required to build

Change-Id: I81c13f4d4f39332ccce3616881ec6e84605ef0ee