Offset: Fix .offset() to correctly work with ShadowDOM

Fixes gh-1784
Close gh-2043

src/offset.js

@@ -39,7 +39,7 @@ jQuery.offset = {
 			elem.style.position = "relative";
 		}
 
-		curOffset = curElem.offset();
+		curOffset = curElem.offset() || { top: 0, left: 0 };
 		curCSSTop = jQuery.css( elem, "top" );
 		curCSSLeft = jQuery.css( elem, "left" );
 		calculatePosition = ( position === "absolute" || position === "fixed" ) &&
@@ -87,8 +87,7 @@ jQuery.fn.extend({
 				});
 		}
 
-		var docElem, win,
-			box = { top: 0, left: 0 },
+		var docElem, win, rect,
 			elem = this[ 0 ],
 			doc = elem && elem.ownerDocument;
 
@@ -96,19 +95,20 @@ jQuery.fn.extend({
 			return;
 		}
 
-		docElem = doc.documentElement;
+		rect = elem.getBoundingClientRect();
 
-		// Make sure it's not a disconnected DOM node
-		if ( !jQuery.contains( docElem, elem ) ) {
-			return box;
-		}
+		// Make sure element is not hidden (display: none) or disconnected
+		if ( rect.width || rect.height || elem.getClientRects().length ) {
+			win = getWindow( doc );
+			docElem = doc.documentElement;
 
-		box = elem.getBoundingClientRect();
-		win = getWindow( doc );
-		return {
-			top: box.top  + ( win.pageYOffset || docElem.scrollTop )  - ( docElem.clientTop  || 0 ),
-			left: box.left + ( win.pageXOffset || docElem.scrollLeft ) - ( docElem.clientLeft || 0 )
-		};
+			return {
+				top: rect.top  + ( win.pageYOffset || docElem.scrollTop ) -
+					( docElem.clientTop  || 0 ),
+				left: rect.left + ( win.pageXOffset || docElem.scrollLeft ) -
+					( docElem.clientLeft || 0 )
+			};
+		}
 	},
 
 	position: function() {

test/unit/offset.js

@@ -57,13 +57,31 @@ test("object without getBoundingClientRect", function() {
 	equal( result.left, 0, "Check left" );
 });
 
-test("disconnected node", function() {
-	expect(2);
+test("disconnected element", function() {
+	expect(1);
 
-	var result = jQuery( document.createElement("div") ).offset();
+	var result;
 
-	equal( result.top, 0, "Check top" );
-	equal( result.left, 0, "Check left" );
+	try {
+		result = jQuery( document.createElement("div") ).offset();
+	} catch ( e ) {}
+
+	ok( !result, "no position for disconnected element" );
+});
+
+test("hidden (display: none) element", function() {
+	expect(1);
+
+	var result,
+		node = jQuery("<div style='display: none' />").appendTo("#qunit-fixture");
+
+	try {
+		result = node.offset();
+	} catch ( e ) {}
+
+	node.remove();
+
+	ok( !result, "no position for hidden (display: none) element" );
 });
 
 testIframe("offset/absolute", "absolute", function($, iframe) {