Make WindowContainer surfaces container layers by default.

This reverts commit f6ef18334b4b90f025fa0ece969c2ce2f92221b1.

Reason for revert: ag/6227549 fixes underlying issue

Change-Id: Id1456529ef0009f8e28575ef591d9559c43db4a5
Fixes: 122561221
Test: go/wm-smoke
13 files changed