Fix boolean attributes as per HTML5 spec

src/dom/DOMPropertyOperations.js

@@ -95,6 +95,9 @@ var DOMPropertyOperations = {
         return '';
       }
       var attributeName = DOMProperty.getAttributeName[name];
+      if (DOMProperty.hasBooleanValue[name]) {
+        return escapeTextForBrowser(attributeName);
+      }
       return processAttributeNameAndPrefix(attributeName) +
         escapeTextForBrowser(value) + '"';
     } else if (DOMProperty.isCustomAttribute(name)) {

src/dom/__tests__/DOMPropertyOperations-test.js

@@ -82,12 +82,12 @@ describe('DOMPropertyOperations', function() {
       expect(DOMPropertyOperations.createMarkupForProperty(
         'checked',
         'simple'
-      )).toBe('checked="simple"');
+      )).toBe('checked');
 
       expect(DOMPropertyOperations.createMarkupForProperty(
         'checked',
         true
-      )).toBe('checked="true"');
+      )).toBe('checked');
 
       expect(DOMPropertyOperations.createMarkupForProperty(
         'checked',