Fixes #12868: Enables icon feedback on validation states for large/small inputs.

Also reorders the CSS to place Glyhpicons as a dependency before other components for fewer overrides and less specific CSS.

less/bootstrap.less

@@ -2,9 +2,10 @@
 @import "variables.less";
 @import "mixins.less";
 
-// Reset
+// Reset and dependencies
 @import "normalize.less";
 @import "print.less";
+@import "glyphicons.less";
 
 // Core CSS
 @import "scaffolding.less";
@@ -17,7 +18,6 @@
 
 // Components
 @import "component-animations.less";
-@import "glyphicons.less";
 @import "dropdowns.less";
 @import "button-groups.less";
 @import "input-groups.less";

less/forms.less

@@ -271,18 +271,27 @@ input[type="checkbox"],
   .form-control {
     padding-right: (@input-height-base * 1.25);
   }
-
-  // Feedback icon (requires .glyphicon classes)
-  .form-control-feedback {
-    position: absolute;
-    top: (@line-height-computed + 5); // Height of the `label` and its margin
-    right: 0;
-    display: block;
-    width: @input-height-base;
-    height: @input-height-base;
-    line-height: @input-height-base;
-    text-align: center;
-  }
+}
+// Feedback icon (requires .glyphicon classes)
+.form-control-feedback {
+  position: absolute;
+  top: (@line-height-computed + 5); // Height of the `label` and its margin
+  right: 0;
+  display: block;
+  width: @input-height-base;
+  height: @input-height-base;
+  line-height: @input-height-base;
+  text-align: center;
+}
+.input-lg + .form-control-feedback {
+  width: @input-height-large;
+  height: @input-height-large;
+  line-height: @input-height-large;
+}
+.input-sm + .form-control-feedback {
+  width: @input-height-small;
+  height: @input-height-small;
+  line-height: @input-height-small;
 }
 
 // Feedback states