Fix graphics corruption in WiFi password dialogs

The ActionBarContextView popup window was set to use the "layout in screen"
and "inset decor" flags even though it's not a fullscreen window. This was
causing the popup window to be created by taking up all the available space.
Because the views inside the popup window are wrap_content, this would cause
part of the window to not be drawn and since the window is, correctly,
marked opaque, we would get random graphics corruption on screen (the user
would see the content of the tiles on a tiled renderer such as QCOM's.)

This change simply removes the two unnecessary flags from the popup window,
forcing it to be created and laid out at the exact size it needs. It will
be properly positioned by the window manager underneath the status bar.
An interesting side effect is that the window is now smaller than before
(since it doesn't extend underneath the status bar) which saves a bit of
memory.

The popup window also contains an unncessary black background behind the
action bar context view. This helps in a way because it allows us to
create an opaque window but it increases the required bandwidth to draw
that window. Given the benefits for SF it's probably best we keep the
window the way it is for now.

Change-Id: I4aeeb42a6232ff6b71811e766846d45635eb3365