Fix 404 on iframe styles by standardizing get and set modules methods.

Change-Id: Iebc2a9fc7db00d661f685c28dbc345fb561bb15e
Merge "Fix 404 on iframe styles by standardizing get and set modules methods."
Create GeneratedContentNode which can store rendered HTML in IV store

AlienNode is now a subclass of GCNode, but doesn't use the IV store yet.

Bug: 46571
Change-Id: If0717afdf557a2aa681d1bae3a6e98299631091a