Fixes #6474: remove duplicate .btn border colors to make @btn-border work

docs/assets/css/bootstrap.css

@@ -3169,11 +3169,11 @@ button.close {
   background-image: -o-linear-gradient(top, #ffffff, #e6e6e6);
   background-image: linear-gradient(to bottom, #ffffff, #e6e6e6);
   background-repeat: repeat-x;
-  border: 1px solid #bbbbbb;
+  border: 1px solid #cccccc;
   *border: 0;
   border-color: #e6e6e6 #e6e6e6 #bfbfbf;
   border-color: rgba(0, 0, 0, 0.1) rgba(0, 0, 0, 0.1) rgba(0, 0, 0, 0.25);
-  border-bottom-color: #a2a2a2;
+  border-bottom-color: #b3b3b3;
   -webkit-border-radius: 4px;
      -moz-border-radius: 4px;
           border-radius: 4px;
@@ -3308,11 +3308,6 @@ input[type="button"].btn-block {
   color: rgba(255, 255, 255, 0.75);
 }
 
-.btn {
-  border-color: #c5c5c5;
-  border-color: rgba(0, 0, 0, 0.15) rgba(0, 0, 0, 0.15) rgba(0, 0, 0, 0.25);
-}
-
 .btn-primary {
   color: #ffffff;
   text-shadow: 0 -1px 0 rgba(0, 0, 0, 0.25);

less/buttons.less

@@ -141,11 +141,6 @@ input[type="button"] {
 
 // Set the backgrounds
 // -------------------------
-.btn {
-  // reset here as of 2.0.3 due to Recess property order
-  border-color: #c5c5c5;
-  border-color: rgba(0,0,0,.15) rgba(0,0,0,.15) rgba(0,0,0,.25);
-}
 .btn-primary {
   .buttonBackground(@btnPrimaryBackground, @btnPrimaryBackgroundHighlight);
 }

less/variables.less

@@ -86,7 +86,7 @@
 // -------------------------
 @btnBackground:                     @white;
 @btnBackgroundHighlight:            darken(@white, 10%);
-@btnBorder:                         #bbb;
+@btnBorder:                         #ccc;
 
 @btnPrimaryBackground:              @linkColor;
 @btnPrimaryBackgroundHighlight:     spin(@btnPrimaryBackground, 20%);