Merge pull request #20684 from twbs/v4-utils

v4: The Utilities Update

scss/mixins/_background-variant.scss

@@ -2,7 +2,6 @@
 
 @mixin bg-variant($parent, $color) {
   #{$parent} {
-    color: #fff !important;
     background-color: $color !important;
   }
   a#{$parent} {

scss/mixins/_float.scss

@@ -1,6 +1,6 @@
-@mixin pull-left {
+@mixin float-left {
   float: left !important;
 }
-@mixin pull-right {
+@mixin float-right {
   float: right !important;
 }

scss/mixins/_image.scss

@@ -7,10 +7,12 @@
 //
 // Keep images from scaling beyond the width of their parents.
 
-@mixin img-fluid($display: block) {
-  display: $display;
-  max-width: 100%; // Part 1: Set a maximum relative to the parent
-  height: auto; // Part 2: Scale the height according to the width, otherwise you get stretching
+@mixin img-fluid {
+  // Part 1: Set a maximum relative to the parent
+  max-width: 100%;
+  // Part 2: Override the height to auto, otherwise images will be stretched
+  // when setting a width and height attribute on the img element.
+  height: auto;
 }