fix(topologies): unify topologies connect API (#1615)

Eliminates the DB parameter from the `connect` call in replset
and mongos to unify the api with server.

BREAKING CHANGE:
Function signature for `.connect` method on replset and mongos has changed. You shouldn't have been using this anyway, but if you were, you only should pass `options` and `callback`.

Part of NODE-1089

Author: daprahamian

lib/topologies/mongos.js

@@ -209,7 +209,7 @@ class Mongos extends TopologyBase {
   }
 
   // Connect
-  connect(db, _options, callback) {
+  connect(_options, callback) {
     var self = this;
     if ('function' === typeof _options) (callback = _options), (_options = {});
     if (_options == null) _options = {};
@@ -218,7 +218,8 @@ class Mongos extends TopologyBase {
     self.s.options = _options;
 
     // Update bufferMaxEntries
-    self.s.storeOptions.bufferMaxEntries = db.bufferMaxEntries;
+    self.s.storeOptions.bufferMaxEntries =
+      typeof _options.bufferMaxEntries === 'number' ? _options.bufferMaxEntries : -1;
 
     // Error handler
     var connectErrorHandler = function() {

lib/topologies/replset.js

@@ -236,7 +236,7 @@ class ReplSet extends TopologyBase {
   }
 
   // Connect method
-  connect(db, _options, callback) {
+  connect(_options, callback) {
     var self = this;
     if ('function' === typeof _options) (callback = _options), (_options = {});
     if (_options == null) _options = {};
@@ -245,7 +245,8 @@ class ReplSet extends TopologyBase {
     self.s.options = _options;
 
     // Update bufferMaxEntries
-    self.s.storeOptions.bufferMaxEntries = db.bufferMaxEntries;
+    self.s.storeOptions.bufferMaxEntries =
+      typeof _options.bufferMaxEntries === 'number' ? _options.bufferMaxEntries : -1;
 
     // Actual handler
     var errorHandler = function(event) {