Remove unnecessary check.

This removed check will never be false as we pass the oplog selector that looks
for 'o.drop' and we assume that you can get only one command per oplog record.

packages/mongo-livedata/oplog.js

@@ -196,12 +196,9 @@ MongoConnection.prototype._observeChangesWithOplog = function (
   var oplogEntryHandle = self._oplogHandle.onOplogEntry(
     cursorDescription.collectionName, function (op) {
       if (op.op === 'c') {
-        // If it is not db.collection.drop(), ignore it
-        if (op.o && _.isEqual(_.keys(op.o), ['drop'])) {
-          published.each(function (fields, id) {
-            remove(id);
-          });
-        }
+        published.each(function (fields, id) {
+          remove(id);
+        });
       } else {
         // All other operators should be handled depending on phase
         oplogEntryHandlers[phase](op);