No ticket: Improve line-height animation test stability

test/unit/effects.js

@@ -1450,7 +1450,8 @@ test("Do not append px to 'fill-opacity' #9548", 1, function() {
 });
 
 asyncTest("line-height animates correctly (#13855)", 12, function() {
-	var longDuration = 2000,
+	var t0,
+		longDuration = 2000,
 		shortDuration = 500,
 		animated = jQuery(
 			"<p style='line-height: 100;'>unitless</p>" +
@@ -1461,10 +1462,14 @@ asyncTest("line-height animates correctly (#13855)", 12, function() {
 		initialHeight = jQuery.map( animated, function( el ) {
 			return jQuery( el ).height();
 		}),
-		tolerance = 1.5,
+		tolerance = 1.5;
+
+	// Delay start to improve test stability
+	setTimeout(function() {
+
 		t0 = +(new Date());
+		animated.animate( { "line-height": "hide" }, longDuration, "linear" );
 
-	animated.animate( { "line-height": "hide" }, longDuration );
 		setTimeout(function() {
 			var progress = ( (new Date()) - t0 ) / longDuration;
 
@@ -1480,7 +1485,9 @@ asyncTest("line-height animates correctly (#13855)", 12, function() {
 			});
 
 			t0 = +(new Date());
-		animated.stop( true, true ).hide().animate( { "line-height": "show" }, longDuration );
+			animated.stop( true, true ).hide()
+					.animate( { "line-height": "show" }, longDuration, "linear" );
+
 			setTimeout(function() {
 				var progress = ( (new Date()) - t0 ) / longDuration;
 
@@ -1497,6 +1504,7 @@ asyncTest("line-height animates correctly (#13855)", 12, function() {
 				start();
 			}, shortDuration );
 		}, shortDuration );
+	}, 50 );
 });
 
 // Start 1.8 Animation tests