Offset: fix iframe scrollTop/Left test for IE8 and iPhone

* IE8 need a doctype, otherwise IE will scroll it, but will
  still show old values. It wasn't noticable before, since IE8 will
  update values if in the dev tools you swtich to "Quirks mode"
  and then back again, then this tab will always show the correct values
  even if you update it

* iPhone resize the iframe by its content regardless of
  the width, height values, meaning it's not possible to scroll
  the iframe only its parent element

Ref ae30fb6c

test/unit/offset.js

@@ -550,17 +550,31 @@ test("fractions (see #7730 and #7885)", function() {
 test("iframe scrollTop/Left (see gh-1945)", function() {
 	expect( 2 );
 
-	// Tests scrollTop/Left with iframes
 	var ifDoc = jQuery( "#iframe" )[ 0 ].contentDocument;
-	jQuery( "#iframe" ).css( "width", "50px" ).css( "height", "50px" );
-	ifDoc.write( "<div style='width: 1000px; height: 1000px;'></div>" );
-	ifDoc.close();
 
-	jQuery( ifDoc ).scrollTop( 200 );
-	jQuery( ifDoc ).scrollLeft( 500 );
+	// iPhone resize the iframe by its content
+	// meaning it's not possible to scroll the iframe only its parent element
+	if ( /iphone os/i.test( navigator.userAgent ) ) {
+		equal( true, true, "iPhone doesn't scroll the iframes" );
+		equal( true, true, "iPhone doesn't scroll the iframes" );
 
-	equal( jQuery( ifDoc ).scrollTop(), 200, "$($('#iframe')[0].contentDocument).scrollTop()" );
-	equal( jQuery( ifDoc ).scrollLeft(), 500, "$($('#iframe')[0].contentDocument).scrollLeft()" );
+	} else {
+		// Tests scrollTop/Left with iframes
+		jQuery( "#iframe" ).css( "width", "50px" ).css( "height", "50px" );
+
+		// Support: IE8
+		// Need a doctype, otherwise IE will scroll it but will still show old values
+		ifDoc.write( "<!DOCTYPE><div style='width: 1000px; height: 1000px;'></div>" );
+
+		// Support: IE8
+		ifDoc.close();
+
+		jQuery( ifDoc ).scrollTop( 200 );
+		jQuery( ifDoc ).scrollLeft( 500 );
+
+		equal( jQuery( ifDoc ).scrollTop(), 200, "$($('#iframe')[0].contentDocument).scrollTop()" );
+		equal( jQuery( ifDoc ).scrollLeft(), 500, "$($('#iframe')[0].contentDocument).scrollLeft()" );
+	}
 });
 
 })();