Fix error when using list as actionBarNavMode. [DO NOT MERGE]

A bug in the framework leads to the wrong argument being passed to
defStyleRes when obtaining styled attributes. The framework however just
ignores the attribute in such a case. LayoutLib logs an error to help
developers find bugs in their code.

The bug was seen when using list as the actionBarNavMode.

This change ignores the attribute if it detects that it's the framework
bug. Also, we change the error to a warning.

Change-Id: I58e1fe4469de0329a27b577d75c0a59c48d0381b