The Faces TCK tests that the el ExpressionFactory instances obtained from the Faces Application object equals the one from the JspFactory. This fails with the EE 10 TCK, which has changed the test deployment to be a CDI deployment (in line with the Faces 4 requirement to use CDI).
The problem is the WeldExpressionFactory.equals method does not properly handle two different instances that have the same delegate. Two such instances are logically equal but the equals method says they are not equal.
I can fix this short term in WildFly by wiring in a subclass of WeldExpressionFactory with a fixed equals method. Then I'll file a Weld issue.