Fixes source editor -> visual editor selection synch regression #3782 
Need to figure out when this regressed and why the "Runtime" reference
does not match what's in the loader's cache.
Undo upgrade from 0.5 to 1.0 in 488a1c9e749914e7f3065e82c1f78b6b5f033cd7
 which seems to have broken the textview setSelection() API used
for synching visual editor selection to source editor. Fixes #3782