Revert "Themes: Build icon cache when applying icons"

This reverts commit 7bb802a478faaac295ccd8b98a3573701edd9b1e.

This is not thread safe.  It is possible for an icon to be in the
middle of being composed when another process requests it.  That
process would not be able to load the image.  In Trebuchet, the
icon would be displayed as the standard "android" icon since it
would not be able to load the icon.

Change-Id: Id9bc38296cc02c376f9ea66565babc00e8dbf634
(cherry picked from commit 92dec234e5ed18afe5cacaf61bcfbe5f311840d3)
Protect windowNoTitle and windowActionBar attributes

This patch creates a new method to define "protected" attributes. These
are attributes like windowActionBar which should not be modified by
a theme.

Some apps (eg gmail) use the appcompat library which
has its own Actionbar classes. When an app uses its own
Actionbar it must not include the default actionbar which is
achieved through the windowActionBar attribute.

Some themes may try to change these attributes, which can will cause
the app to crash.

Change-Id: Ie3bb7285eed09f3f13facf9d142ea9eb83796eec
(cherry picked from commit 9a6496249d68b2b5a72cb14425b53d772b6fe1db)