Examples that currently fail:
Given the shadowing logic of the compiler is pretty expensive and further dynamically computing the munged name of each "first namespace segment" could potentially slow down the compiler by a factor of 2x (or more) we should probably re-introduce this approach:
Ie, maintaining a set of first ns segments and do s simple set lookup in shadow-depth. We should probably only store munged names and do the lookup after munging to fix the above bugs. We should also add "goog".