Only top level JS annotations should be allowed to contain dots

[jacob314]

The following should generate a static error as the @JS annotation for location is not top level but contains a dot.

@JS('goog.maps')
class Maps {
  @JS('current.loc');
  external static location;
}

If you want to access location as a static you should instead be required to write

@JS('goog.maps.current')
class Current {
  @JS('loc');
  external static location;
}

There isn't much benefit from supporting dot within @JS annotations on static member names the meaning
of static @JS annotations containing dots is confusing.

[daniel-v]

Just ran into this. DDC warned me with a link to this issue. Big, big 👍 for properly informing me about it.