Tooltip: Avoid creating an unnecessary tooltip when `Tooltip#hide` is called

Fixed performance bug where a tooltip element is created and then immediately destroyed when tooltip.hide() is called and there is no existing tooltip element

Resolves #15557 by merging it.

js/tooltip.js

@@ -292,7 +292,7 @@
 
   Tooltip.prototype.hide = function (callback) {
     var that = this
-    var $tip = this.tip()
+    var $tip = $(this.$tip)
     var e    = $.Event('hide.bs.' + this.type)
 
     function complete() {
@@ -309,7 +309,7 @@
 
     $tip.removeClass('in')
 
-    $.support.transition && this.$tip.hasClass('fade') ?
+    $.support.transition && $tip.hasClass('fade') ?
       $tip
         .one('bsTransitionEnd', complete)
         .emulateTransitionEnd(Tooltip.TRANSITION_DURATION) :