Make DimLayer size dependent on stack layout.

Only use the stack bounds for the DimLayer bounds if there is more
than one stack on a layer. Otherwise cover the entire screen (and
more) with the DimLayer. This way there are no exposed regions when
rotating.

Fixes bug 10428085.

Change-Id: I7bfff12b69d59e86610621c498dab35cf0db8eb5
2 files changed