Don't depend on iframe load events

It was discovered that nested iframes inside firefox do not fire load
events: http://osdir.com/ml/dev-apps-firefox/2010-03/msg00134.html

Since we no longer care when the iframe is loaded, changing the frame
onLoad method name to load and manually calling it was sufficient.

Bug: 50115

Change-Id: I65c0c404a2a384566701b1c6b1bb978e0b99c90d
Merge "Don't depend on iframe load events"