Fixes #10620: remove gradient on buttons for IE9 in theme.less due to bleed...

Fixes #10620: remove gradient on buttons for IE9 in theme.less due to bleed through with rounded corners

dist/css/bootstrap-theme.css

@@ -47,6 +47,7 @@
   border-color: #dbdbdb;
   border-color: #ccc;
   filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#ffffffff', endColorstr='#ffe0e0e0', GradientType=0);
+  filter: progid:DXImageTransform.Microsoft.gradient(enabled=false);
 }
 
 .btn-default:hover,
@@ -69,6 +70,7 @@
   background-repeat: repeat-x;
   border-color: #2b669a;
   filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#ff428bca', endColorstr='#ff2d6ca2', GradientType=0);
+  filter: progid:DXImageTransform.Microsoft.gradient(enabled=false);
 }
 
 .btn-primary:hover,
@@ -91,6 +93,7 @@
   background-repeat: repeat-x;
   border-color: #3e8f3e;
   filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#ff5cb85c', endColorstr='#ff419641', GradientType=0);
+  filter: progid:DXImageTransform.Microsoft.gradient(enabled=false);
 }
 
 .btn-success:hover,
@@ -113,6 +116,7 @@
   background-repeat: repeat-x;
   border-color: #e38d13;
   filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#fff0ad4e', endColorstr='#ffeb9316', GradientType=0);
+  filter: progid:DXImageTransform.Microsoft.gradient(enabled=false);
 }
 
 .btn-warning:hover,
@@ -135,6 +139,7 @@
   background-repeat: repeat-x;
   border-color: #b92c28;
   filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#ffd9534f', endColorstr='#ffc12e2a', GradientType=0);
+  filter: progid:DXImageTransform.Microsoft.gradient(enabled=false);
 }
 
 .btn-danger:hover,
@@ -157,6 +162,7 @@
   background-repeat: repeat-x;
   border-color: #28a4c9;
   filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#ff5bc0de', endColorstr='#ff2aabd2', GradientType=0);
+  filter: progid:DXImageTransform.Microsoft.gradient(enabled=false);
 }
 
 .btn-info:hover,

less/theme.less

@@ -33,6 +33,7 @@
 // Mixin for generating new styles
 .btn-styles(@btn-color: #555) {
   #gradient > .vertical(@start-color: @btn-color; @end-color: darken(@btn-color, 12%));
+  .reset-filter(); // Disable gradients for IE9 because filter bleeds through rounded corners
   background-repeat: repeat-x;
   border-color: darken(@btn-color, 14%);