Correct scope resolution for single-ident paths and correct receiver for bound events.

This patch implements two corrections related to name resolution within named scopes:

1) single-ident paths must be bound directly to the proper scope object in case of
-two-way binding (so that the pushed value affects the correct model)
-event handlers which don't expect their |this| value to have the correct identity.

2) bound events must resolve their receiver as the object which directly references the target function.

R=arv
BUG=

Review URL: https://codereview.appspot.com/51140045