Fixes #9150: Hide popover titles in IE8

Properly hides popover titles in IE8 because apparently it doesn't
accept the `:empty` selector. /cc @fat @cvrebert

dist/js/bootstrap.js

@@ -1503,7 +1503,13 @@ if (!jQuery) { throw new Error("Bootstrap requires jQuery") }
 
     $tip.removeClass('fade top bottom left right in')
 
-    $tip.find('.popover-title:empty').hide()
+    // Hide empty titles
+    //
+    // IE8 doesn't accept hiding via the `:empty` pseudo selector, we have to do
+    // this manually by checking the contents.
+    if ($tip.find('.popover-title').html() === '') {
+      $tip.find('.popover-title').hide();
+    }
   }
 
   Popover.prototype.hasContent = function () {

javascript.html

@@ -963,16 +963,16 @@ $('#myTooltip').on('hidden.bs.tooltip', function () {
     <h4>Four directions</h4>
     <div class="bs-example tooltip-demo">
       <div class="bs-example-tooltips">
-        <button type="button" class="btn btn-default" data-toggle="popover" data-placement="left" data-content="Vivamus sagittis lacus vel augue laoreet rutrum faucibus.">
+        <button type="button" class="btn btn-default" data-container="body" data-toggle="popover" data-placement="left" data-content="Vivamus sagittis lacus vel augue laoreet rutrum faucibus.">
           Popover on left
         </button>
-        <button type="button" class="btn btn-default" data-toggle="popover" data-placement="top" data-content="Vivamus sagittis lacus vel augue laoreet rutrum faucibus.">
+        <button type="button" class="btn btn-default" data-container="body" data-toggle="popover" data-placement="top" data-content="Vivamus sagittis lacus vel augue laoreet rutrum faucibus.">
           Popover on top
         </button>
-        <button type="button" class="btn btn-default" data-toggle="popover" data-placement="bottom" data-content="Vivamus sagittis lacus vel augue laoreet rutrum faucibus.">
+        <button type="button" class="btn btn-default" data-container="body" data-toggle="popover" data-placement="bottom" data-content="Vivamus sagittis lacus vel augue laoreet rutrum faucibus.">
           Popover on bottom
         </button>
-        <button type="button" class="btn btn-default" data-toggle="popover" data-placement="right" data-content="Vivamus sagittis lacus vel augue laoreet rutrum faucibus.">
+        <button type="button" class="btn btn-default" data-container="body" data-toggle="popover" data-placement="right" data-content="Vivamus sagittis lacus vel augue laoreet rutrum faucibus.">
           Popover on right
         </button>
       </div>

js/popover.js

@@ -58,7 +58,13 @@
 
     $tip.removeClass('fade top bottom left right in')
 
-    $tip.find('.popover-title:empty').hide()
+    // Hide empty titles
+    //
+    // IE8 doesn't accept hiding via the `:empty` pseudo selector, we have to do
+    // this manually by checking the contents.
+    if ($tip.find('.popover-title').html() === '') {
+      $tip.find('.popover-title').hide();
+    }
   }
 
   Popover.prototype.hasContent = function () {