Merge branch 'master' into pr/11817

Conflicts:
	dist/css/bootstrap.min.css
	less/input-groups.less

less/input-groups.less

@@ -17,6 +17,11 @@
   }
 
   .form-control {
+    // IE9 fubars the placeholder attribute in text inputs and the arrows on
+    // select elements in input groups. To fix it, we float the input. Details:
+    // https://github.com/twbs/bootstrap/issues/11561#issuecomment-28936855
+    float: left;
+
     width: 100%;
     margin-bottom: 0;
   }
@@ -112,10 +117,25 @@
 // -------------------------
 .input-group-btn {
   position: relative;
-  // Jankily prevent input button groups from wrapping
-  white-space: nowrap;
-  // in combination with inline-blocks and nowrap, space characters would take visible space
+  // Jankily prevent input button groups from wrapping with `white-space` and
+  // `font-size` in combination with `inline-block` on buttons.
   font-size: 0;
+  white-space: nowrap;
+
+  // Negative margin for spacing, position for bringing hovered/focused/actived
+  // element above the siblings.
+  > .btn {
+    position: relative;
+    + .btn {
+      margin-left: -1px;
+    }
+    // Bring the "active" button to the front
+    &:hover,
+    &:focus,
+    &:active {
+      z-index: 2;
+    }
+  }
 
   // Negative margin to only have a 1px border between the two
   &:first-child > .btn {
@@ -125,14 +145,3 @@
     margin-left: -1px;
   }
 }
-.input-group-btn > .btn {
-  position: relative;
-  + .btn {
-    margin-left: -1px;
-  }
-  // Bring the "active" button to the front
-  &:hover,
-  &:active {
-    z-index: 2;
-  }
-}