Index: src/wp-includes/css/media-views.css
===================================================================
--- src/wp-includes/css/media-views.css	(revision 32001)
+++ src/wp-includes/css/media-views.css	(working copy)
@@ -1494,7 +1494,6 @@
 	background: url(../images/spinner.gif) no-repeat;
 	-webkit-background-size: 20px 20px;
 	background-size: 20px 20px;
-	display: none;
 	opacity: 0.7;
 	filter: alpha(opacity=70);
 	width: 20px;
Index: src/wp-includes/js/media/views/attachments/browser.js
===================================================================
--- src/wp-includes/js/media/views/attachments/browser.js	(revision 32001)
+++ src/wp-includes/js/media/views/attachments/browser.js	(working copy)
@@ -306,18 +306,18 @@
 		}
 
 		if ( ! this.collection.length ) {
-			this.toolbar.get( 'spinner' ).show();
+			this.toolbar.get( 'spinner' ).$el.addClass( 'is-active' );
 			this.dfd = this.collection.more().done( function() {
 				if ( ! view.collection.length ) {
 					noItemsView.$el.removeClass( 'hidden' );
 				} else {
 					noItemsView.$el.addClass( 'hidden' );
 				}
-				view.toolbar.get( 'spinner' ).hide();
+				view.toolbar.get( 'spinner' ).$el.removeClass( 'is-active' );
 			} );
 		} else {
 			noItemsView.$el.addClass( 'hidden' );
-			view.toolbar.get( 'spinner' ).hide();
+			view.toolbar.get( 'spinner' ).$el.removeClass( 'is-active' );
 		}
 	},
 
Index: src/wp-includes/js/media/views/attachments.js
===================================================================
--- src/wp-includes/js/media/views/attachments.js	(revision 32001)
+++ src/wp-includes/js/media/views/attachments.js	(working copy)
@@ -284,13 +284,13 @@
 
 		// Show the spinner only if we are close to the bottom.
 		if ( el.scrollHeight - ( scrollTop + el.clientHeight ) < el.clientHeight / 3 ) {
-			toolbar.get('spinner').show();
+			toolbar.get('spinner').$el.addClass( 'is-active' );
 		}
 
 		if ( el.scrollHeight < scrollTop + ( el.clientHeight * this.options.refreshThreshold ) ) {
 			this.collection.more().done(function() {
 				view.scroll();
-				toolbar.get('spinner').hide();
+				toolbar.get('spinner').$el.removeClass( 'is-active' );
 			});
 		}
 	}
Index: src/wp-includes/js/media/views/embed/link.js
===================================================================
--- src/wp-includes/js/media/views/embed/link.js	(revision 32001)
+++ src/wp-includes/js/media/views/embed/link.js	(working copy)
@@ -34,7 +34,7 @@
 			return;
 		}
 
-		this.spinner.show();
+		this.spinner.addClass( 'is-active' );
 
 		this.fetch();
 	}, 600 ),
@@ -95,7 +95,7 @@
 			this.model.unset( 'width', opts );
 		}
 
-		this.spinner.hide();
+		this.spinner.removeClass( 'is-active' );
 
 		this.$('.embed-container').show().find('.embed-preview').html( html );
 	}
Index: src/wp-includes/js/media/views/spinner.js
===================================================================
--- src/wp-includes/js/media/views/spinner.js	(revision 32001)
+++ src/wp-includes/js/media/views/spinner.js	(working copy)
@@ -17,7 +17,7 @@
 	show: function() {
 		if ( ! this.spinnerTimeout ) {
 			this.spinnerTimeout = _.delay(function( $el ) {
-				$el.show();
+				$el.addClass( 'is-active' );
 			}, this.delay, this.$el );
 		}
 
@@ -25,7 +25,7 @@
 	},
 
 	hide: function() {
-		this.$el.hide();
+		this.$el.removeClass( 'is-active' );
 		this.spinnerTimeout = clearTimeout( this.spinnerTimeout );
 
 		return this;
Index: src/wp-includes/js/media/views.js
===================================================================
--- src/wp-includes/js/media/views.js	(revision 32001)
+++ src/wp-includes/js/media/views.js	(working copy)
@@ -3655,13 +3655,13 @@
 
 		// Show the spinner only if we are close to the bottom.
 		if ( el.scrollHeight - ( scrollTop + el.clientHeight ) < el.clientHeight / 3 ) {
-			toolbar.get('spinner').show();
+			toolbar.get('spinner').$el.addClass( 'is-active' );
 		}
 
 		if ( el.scrollHeight < scrollTop + ( el.clientHeight * this.options.refreshThreshold ) ) {
 			this.collection.more().done(function() {
 				view.scroll();
-				toolbar.get('spinner').hide();
+				toolbar.get('spinner').$el.removeClass( 'is-active' );
 			});
 		}
 	}
@@ -3978,18 +3978,18 @@
 		}
 
 		if ( ! this.collection.length ) {
-			this.toolbar.get( 'spinner' ).show();
+			this.toolbar.get( 'spinner' ).$el.addClass( 'is-active' );
 			this.dfd = this.collection.more().done( function() {
 				if ( ! view.collection.length ) {
 					noItemsView.$el.removeClass( 'hidden' );
 				} else {
 					noItemsView.$el.addClass( 'hidden' );
 				}
-				view.toolbar.get( 'spinner' ).hide();
+				view.toolbar.get( 'spinner').$el.removeClass( 'is-active' );
 			} );
 		} else {
 			noItemsView.$el.addClass( 'hidden' );
-			view.toolbar.get( 'spinner' ).hide();
+			view.toolbar.get( 'spinner').$el.removeClass( 'is-active' );
 		}
 	},
 
@@ -4546,7 +4546,7 @@
 			return;
 		}
 
-		this.spinner.show();
+		this.spinner.addClass( 'is-active' );
 
 		this.fetch();
 	}, 600 ),
@@ -4607,7 +4607,7 @@
 			this.model.unset( 'width', opts );
 		}
 
-		this.spinner.hide();
+		this.spinner.removeClass( 'is-active' );
 
 		this.$('.embed-container').show().find('.embed-preview').html( html );
 	}
@@ -7463,7 +7463,7 @@
 	show: function() {
 		if ( ! this.spinnerTimeout ) {
 			this.spinnerTimeout = _.delay(function( $el ) {
-				$el.show();
+				$el.addClass( 'is-active' );
 			}, this.delay, this.$el );
 		}
 
@@ -7471,7 +7471,7 @@
 	},
 
 	hide: function() {
-		this.$el.hide();
+		this.$el.removeClass( 'is-active' );
 		this.spinnerTimeout = clearTimeout( this.spinnerTimeout );
 
 		return this;