Comment 62 for bug 306017

My assumption was that LOAD_LINK/LOAD_FLAGS_IS_LINK would be strictly for links and form submissions; the new flag gets used by some JS and chrome loads.

The problem being solved is that each load requires either:

1. persisting the search if it's part of an existing browsing activity
2. resetting the search if it's the start of a new browsing activity

This approach adds the flag to type-1 loads (fewer of that type). The flag eventually gets translated to a web progress flag that's listened for in the tabbrowser location change listener.