fix(tooltip): don't use an empty transclusion fn

Closes #2825

src/tooltip/tooltip.js

@@ -186,7 +186,7 @@ angular.module( 'ui.bootstrap.tooltip', [ 'ui.bootstrap.position', 'ui.bootstrap
               // Set the initial positioning.
               tooltip.css({ top: 0, left: 0, display: 'block' });
 
-              // Now we add it to the DOM because need some info about it. But it's not 
+              // Now we add it to the DOM because need some info about it. But it's not
               // visible yet anyway.
               if ( appendToBody ) {
                   $document.find( 'body' ).append( tooltip );
@@ -214,7 +214,7 @@ angular.module( 'ui.bootstrap.tooltip', [ 'ui.bootstrap.position', 'ui.bootstrap
               $timeout.cancel( popupTimeout );
               popupTimeout = null;
 
-              // And now we remove it from the DOM. However, if we have animation, we 
+              // And now we remove it from the DOM. However, if we have animation, we
               // need to wait for it to expire beforehand.
               // FIXME: this is a placeholder for a port of the transitions library.
               if ( scope.tt_animation ) {
@@ -231,10 +231,7 @@ angular.module( 'ui.bootstrap.tooltip', [ 'ui.bootstrap.position', 'ui.bootstrap
               if (tooltip) {
                 removeTooltip();
               }
-              tooltip = tooltipLinker(scope, function () {});
-
-              // Get contents rendered into the tooltip
-              scope.$digest();
+              tooltip = tooltipLinker(scope);
             }
 
             function removeTooltip() {