Fix #13543. offsetWidth is wrong on non-1 zoom. Close gh-1194.

src/core.js

@@ -781,7 +781,30 @@ jQuery.extend({
 				length ? fn( elems[0], key ) : emptyGet;
 	},
 
-	now: Date.now
+	now: Date.now,
+
+	// A method for quickly swapping in/out CSS properties to get correct calculations.
+	// Note: this method belongs to the css module but it's needed here for the support module.
+	// If support gets modularized, this method should be moved back to the css module.
+	swap: function( elem, options, callback, args ) {
+		var ret, name,
+			old = {};
+
+		// Remember the old values, and insert the new ones
+		for ( name in options ) {
+			old[ name ] = elem.style[ name ];
+			elem.style[ name ] = options[ name ];
+		}
+
+		ret = callback.apply( elem, args || [] );
+
+		// Revert the old values
+		for ( name in options ) {
+			elem.style[ name ] = old[ name ];
+		}
+
+		return ret;
+	}
 });
 
 jQuery.ready.promise = function( obj ) {

src/css.js

@@ -277,27 +277,6 @@ jQuery.extend({
 			return extra === true || jQuery.isNumeric( num ) ? num || 0 : val;
 		}
 		return val;
-	},
-
-	// A method for quickly swapping in/out CSS properties to get correct calculations
-	swap: function( elem, options, callback, args ) {
-		var ret, name,
-			old = {};
-
-		// Remember the old values, and insert the new ones
-		for ( name in options ) {
-			old[ name ] = elem.style[ name ];
-			elem.style[ name ] = options[ name ];
-		}
-
-		ret = callback.apply( elem, args || [] );
-
-		// Revert the old values
-		for ( name in options ) {
-			elem.style[ name ] = old[ name ];
-		}
-
-		return ret;
 	}
 });
 

src/support.js

@@ -75,12 +75,16 @@ jQuery.support = (function( support ) {
 		container = document.createElement("div");
 		container.style.cssText = "border:0;width:0;height:0;position:absolute;top:0;left:-9999px;margin-top:1px";
 
-		// Check box-sizing and margin behavior
+		// Check box-sizing and margin behavior.
 		body.appendChild( container ).appendChild( div );
 		div.innerHTML = "";
 		div.style.cssText = "box-sizing:border-box;-moz-box-sizing:border-box;-webkit-box-sizing:border-box;padding:1px;border:1px;display:block;width:4px;margin-top:1%;position:absolute;top:1%;";
 
-		support.boxSizing = div.offsetWidth === 4;
+		// Workaround failing boxSizing test due to offsetWidth returning wrong value
+		// with some non-1 values of body zoom, ticket #13543
+		jQuery.swap( body, body.style.zoom != null ? { zoom: 1 } : {}, function() {
+			support.boxSizing = div.offsetWidth === 4;
+		});
 		support.doesNotIncludeMarginInBodyOffset = body.offsetTop !== 1;
 
 		// Use window.getComputedStyle because jsdom on node.js will break without it.

test/data/support/boxSizing.html

+<!DOCTYPE html>
+<html>
+<head>
+    <meta charset="utf-8">
+    <style>
+        body {
+            zoom: 0.87;
+        }
+    </style>
+</head>
+<body>
+<script src="../../jquery.js"></script>
+<script>
+    jQuery(function() {
+        window.parent.iframeCallback( jQuery.support.boxSizing );
+    });
+</script>
+</body>
+</html>

test/unit/support.js

@@ -19,6 +19,11 @@ if ( jQuery.css ) {
 	});
 }
 
+testIframeWithCallback( "A non-1 zoom on body doesn't cause WebKit to fail box-sizing test", "support/boxSizing.html", function( boxSizing ) {
+	expect( 1 );
+	equal( boxSizing, jQuery.support.boxSizing, "box-sizing properly detected on page with non-1 body zoom" );
+});
+
 testIframeWithCallback( "A background on the testElement does not cause IE8 to crash (#9823)", "support/testElementCrash.html", function() {
 	expect( 1 );
 	ok( true, "IE8 does not crash" );