DOMTokenList.contains() should not throw.

third_party/WebKit/LayoutTests/fast/dom/HTMLElement/resources/class-list.js

 description('Tests the classList attribute and its properties.');
 
 var element;
 
 function createElement(className)
 {
     element = document.createElement('p');
     element.className = className;
 }
 
@@ skipping 136 matching lines @@
             testFailed('Wrong exception code: ' + ex.code);
             return;
         }
     }
     var formattedFunction = String(f).replace(/^function.+\{\s*/m, '').
         replace(/;?\s+\}/m, '');
     testPassed(formattedFunction + ' threw expected DOMException with code ' + ec);
 }
 
 createElement('x');
-shouldThrowDOMException(function() {
-    element.classList.contains('');
-}, DOMException.SYNTAX_ERR);
+shouldNotThrow('element.classList.contains("")');
 
 createElement('x y');
-shouldThrowDOMException(function() {
-    element.classList.contains('x y');
-}, DOMException.INVALID_CHARACTER_ERR);
+shouldNotThrow('element.classList.contains("x y")');
 
 createElement('');
 shouldThrowDOMException(function() {
     element.classList.add('');
 }, DOMException.SYNTAX_ERR);
 
 createElement('');
 shouldThrowDOMException(function() {
     element.classList.add('x y');
 }, DOMException.INVALID_CHARACTER_ERR);
@@ skipping 193 matching lines @@
 element.classList.remove('a', 'c');
 shouldBe('observer.takeRecords().length', '1');
 
 // iterable<DOMString>;
 createElement('a b c');
 var seen = [];
 for (var t of element.classList) {
     seen.push(t);
 }
 shouldBeTrue("areArraysEqual(seen, ['a', 'b', 'c'])");