Add support check, added assertion to check if cleared, add edge case for backgroundPosition

src/css.js

@@ -204,6 +204,9 @@ jQuery.extend({
 
 			// If a hook was provided, use that value, otherwise just set the specified value
 			if ( !hooks || !("set" in hooks) || (value = hooks.set( elem, value, extra )) !== undefined ) {
+				// IE9/10 Clearing Cloned Style Clear's Original Style. Fixes bug #8908
+				value = !jQuery.support.clearCloneStyle && value === "" && name.match( /backgroundPosition/ ) ? "0% 0%" : value;
+
 				// Wrapped to prevent IE from throwing errors when 'invalid' values are provided
 				// Fixes bug #5509
 				try {

src/manipulation.js

@@ -585,14 +585,13 @@ jQuery.extend({
 		var srcElements,
 			destElements,
 			i,
-			clone,
-			fix8908;
+			clone;
 
 		if ( jQuery.support.html5Clone || jQuery.isXMLDoc(elem) || !rnoshimcache.test( "<" + elem.nodeName + ">" ) ) {
 			// Fixes #8909 - By accessing one of the element's computed styles it breaks the
 			// connection with the cloned element's styles in IE9/10
-			if ( elem.nodeType === 1 && window.getComputedStyle ) {
-				fix8908 = ( window.getComputedStyle( elem, null ) || {} ).backgroundImage;
+			if ( !jQuery.support.clearCloneStyle && elem.nodeType === 1 && window.getComputedStyle ) {
+				i = ( window.getComputedStyle( elem, null ) || {} ).backgroundPosition;
 			}
 
 			clone = elem.cloneNode( true );

src/support.js

@@ -170,6 +170,19 @@ jQuery.support = (function() {
 		}
 	}
 
+	support.clearCloneStyle = (function() {
+		var source = document.createElement( "div" ),
+			styleName = "backgroundClip",
+			value = "content-box",
+			clone;
+
+		source.style[ styleName ] = value;
+		clone = source.cloneNode( true );
+		clone.style[ styleName ] = "";
+
+		return source.style[ styleName ] === value;
+	})();
+
 	// Run tests that need a body at doc ready
 	jQuery(function() {
 		var container, div, tds, marginDiv,

test/unit/manipulation.js

@@ -1909,18 +1909,18 @@ test("checked state is cloned with clone()", function(){
 });
 
 test( "Clearing a Cloned Element's Style Shouldn't Clear the Original Element's Style (#8908)", function() {
-	expect( 8 );
+	expect( 16 );
 
 	var baseUrl = document.location.href.replace( /([^\/]*)$/, "" );
 	var styles = [
-		{ name: "background-attachment", value: [ "fixed" ], expected: [ "scroll" ] },
-		{ name: "background-color", value: [ "rgb(255, 0, 0)", "rgb(255,0,0)" ], expected: [ "transparent" ] },
-		{ name: "background-image", value: [ 'url("test.png")', 'url(' + baseUrl + 'test.png)', 'url("' + baseUrl + 'test.png")' ], expected: [ "none" ] },
-		{ name: "background-position", value: [ "5% 5%" ], expected: [ "0% 0%" ] },
-		{ name: "background-repeat", value: [ "repeat-y" ], expected: [ "repeat" ] },
-		{ name: "background-clip", value: [ "content-box" ], expected: [ "border-box" ] },
-		{ name: "background-origin", value: [ "content-box" ], expected: [ "padding-box" ] },
-		{ name: "background-size", value: [ "80px 60px" ], expected: [] }
+		{ name: "backgroundAttachment", value: [ "fixed" ], expected: [ "scroll" ] },
+		{ name: "backgroundColor", value: [ "rgb(255, 0, 0)", "rgb(255,0,0)", "#ff0000" ], expected: [ "transparent" ] },
+		{ name: "backgroundImage", value: [ 'url("test.png")', 'url(' + baseUrl + 'test.png)', 'url("' + baseUrl + 'test.png")' ], expected: [ "none", 'url("http://static.jquery.com/files/rocker/images/logo_jquery_215x53.gif")' ] }, // Firefox returns auto's value
+		{ name: "backgroundPosition", value: [ "5% 5%" ], expected: [ "0% 0%", "-1000px 0px", "-1000px 0%" ] },
+		{ name: "backgroundRepeat", value: [ "repeat-y" ], expected: [ "repeat", "no-repeat" ] }, // Firefox returns no-repeat
+		{ name: "backgroundClip", value: [ "padding-box" ], expected: [ "border-box" ] },
+		{ name: "backgroundOrigin", value: [ "content-box" ], expected: [ "padding-box" ] },
+		{ name: "backgroundSize", value: [ "80px 60px" ], expected: [ "auto auto" ] }
 	];
 
 	jQuery.each( styles, function(index, style) {
@@ -1931,6 +1931,7 @@ test( "Clearing a Cloned Element's Style Shouldn't Clear the Original Element's
 		source = $source[ 0 ];
 		if ( source.style[ style.name ] === undefined ) {
 			ok( true, style.name +  ": style isn't supported and therefore not an issue" );
+			ok( true );
 			return true;
 		}
 		$source.css( style.name, style.value[0] );
@@ -1941,5 +1942,9 @@ test( "Clearing a Cloned Element's Style Shouldn't Clear the Original Element's
 			"Clearning clone.css() doesn't affect source.css(): " + style.name +
 			"; result: " + $source.css( style.name ) +
 			"; expected: " + style.value.join( "," ) );
+		ok( ~jQuery.inArray( $clone.css( style.name ), style.expected ),
+			"The cloned element was reset to it's default value: " + style.name +
+			"; result: " + $clone.css( style.name ) +
+			"; expected: " + style.expected.join( "," ) );
 	});
 });
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