Fix zooming in preview

Port of:
https://github.com/Dorregaray/camerahal/commit/6ba7ef41c386aa16dbac9aab1922dc3bbbd99eba
Use classic webview

 * Workaround for glitches the new chrome stuff causes on our device

  Requires these patches:

    http://review.cyanogenmod.org/#/c/56054/
    http://review.cyanogenmod.org/#/c/56055/

  And also the webkit folder must be put back in external

Conflicts:

	system.prop
Revert "Disable render dirty regions"

This reverts commit 2a95e117830c47121974e99b1533952ac0ffb1b9.
Revert "Use classic webview"

This reverts commit e99a162c86ff8b9a477c18321b8af652f4d48e79.