diff --git src/wp-includes/js/wp-emoji-loader.js src/wp-includes/js/wp-emoji-loader.js
index 5ddea9f..0b474f8 100644
--- src/wp-includes/js/wp-emoji-loader.js
+++ src/wp-includes/js/wp-emoji-loader.js
@@ -1,25 +1,33 @@
 ( function( window, document, settings ) {
 	var src, ready, ii, tests;
 
+	/*
+	 * Create a canvas element for testing native browser support
+	 * of emoji.
+	 */
+	var canvas = document.createElement( 'canvas' );
+	var context = canvas.getContext && canvas.getContext( '2d' );
+
 	/**
 	 * Detect if the browser supports rendering emoji or flag emoji. Flag emoji are a single glyph
 	 * made of two characters, so some browsers (notably, Firefox OS X) don't support them.
 	 *
 	 * @since 4.2.0
 	 *
-	 * @param type {String} Whether to test for support of "simple", "flag", "diversity" or "unicode8" emoji.
+	 * @param type {String} Whether to test for support of "flag" or "emoji4" emoji.
 	 * @return {Boolean} True if the browser can render emoji, false if it cannot.
 	 */
 	function browserSupportsEmoji( type ) {
-		var canvas = document.createElement( 'canvas' ),
-			context = canvas.getContext && canvas.getContext( '2d' ),
-			stringFromCharCode = String.fromCharCode,
-			flag, flag2, tonedata, tone, tone2, technologist, technologist2;
+		var stringFromCharCode = String.fromCharCode,
+			flag, flag2, technologist, technologist2;
 
 		if ( ! context || ! context.fillText ) {
 			return false;
 		}
 
+		// Cleanup from previous test.
+		context.clearRect( 0, 0, canvas.width, canvas.height );
+
 		/*
 		 * Chrome on OS X added native emoji rendering in M41. Unfortunately,
 		 * it doesn't work when the font is bolder than 500 weight. So, we
@@ -33,13 +41,13 @@
 				/*
 				 * This works because the image will be one of three things:
 				 * - Two empty squares, if the browser doesn't render emoji
-				 * - Two squares with 'A' and 'U' in them, if the browser doesn't render flag emoji
-				 * - The Australian flag
+				 * - Two squares with 'U' and 'N' in them, if the browser doesn't render flag emoji
+				 * - The United Nations flag
 				 *
 				 * The first two will encode to small images (1-2KB data URLs), the third will encode
 				 * to a larger image (4-5KB data URL).
 				 */
-				context.fillText( stringFromCharCode( 55356, 56806, 55356, 56826 ), 0, 0 );
+				context.fillText( stringFromCharCode( 55356, 56826, 55356, 56819 ), 0, 0 );
 				if ( canvas.toDataURL().length < 3000 ) {
 					return false;
 				}
@@ -63,45 +71,6 @@
 				flag2 = canvas.toDataURL();
 
 				return flag !== flag2;
-			case 'diversity':
-				/*
-				 * This tests if the browser supports the Emoji Diversity specification, by rendering an
-				 * emoji with no skin tone specified (in this case, Santa). It then adds a skin tone, and
-				 * compares if the emoji rendering has changed.
-				 */
-				context.fillText( stringFromCharCode( 55356, 57221 ), 0, 0 );
-				tonedata = context.getImageData( 16, 16, 1, 1 ).data;
-				tone = tonedata[0] + ',' + tonedata[1] + ',' + tonedata[2] + ',' + tonedata[3];
-
-				context.fillText( stringFromCharCode( 55356, 57221, 55356, 57343 ), 0, 0 );
-				// Chrome has issues comparing arrays, and Safari has issues converting arrays to strings.
-				// So, we create our own string and compare that, instead.
-				tonedata = context.getImageData( 16, 16, 1, 1 ).data;
-				tone2 = tonedata[0] + ',' + tonedata[1] + ',' + tonedata[2] + ',' + tonedata[3];
-
-				return tone !== tone2;
-			case 'simple':
-				/*
-				 * This creates a smiling emoji, and checks to see if there is any image data in the
-				 * center pixel. In browsers that don't support emoji, the character will be rendered
-				 * as an empty square, so the center pixel will be blank.
-				 */
-				context.fillText( stringFromCharCode( 55357, 56835 ), 0, 0 );
-				return context.getImageData( 16, 16, 1, 1 ).data[0] !== 0;
-			case 'unicode8':
-				/*
-				 * To check for Unicode 8 support, let's try rendering the most important advancement
-				 * that the Unicode Consortium have made in years: the burrito.
-				 */
-				context.fillText( stringFromCharCode( 55356, 57135 ), 0, 0 );
-				return context.getImageData( 16, 16, 1, 1 ).data[0] !== 0;
-			case 'unicode9':
-				/*
-				 * Do Unicode 9 emoji render?
-				 * ¯\_(ツ)_/¯
-				 */
-				context.fillText( stringFromCharCode( 55358, 56631 ), 0, 0 );
-				return context.getImageData( 16, 16, 1, 1 ).data[0] !== 0;
 			case 'emoji4':
 				/*
 				 * Emoji 4 has the best technologists. So does WordPress!
@@ -128,11 +97,11 @@
 		var script = document.createElement( 'script' );
 
 		script.src = src;
-		script.type = 'text/javascript';
+		script.defer = script.type = 'text/javascript';
 		document.getElementsByTagName( 'head' )[0].appendChild( script );
 	}
 
-	tests = Array( 'simple', 'flag', 'unicode8', 'diversity', 'unicode9', 'emoji4' );
+	tests = Array( 'flag', 'emoji4' );
 
 	settings.supports = {
 		everything: true,