Remove TreatNullAs=NullString for various HTML elements

LayoutTests/fast/dom/element-attribute-js-null.html

Index: LayoutTests/fast/dom/element-attribute-js-null.html
diff --git a/LayoutTests/fast/dom/element-attribute-js-null.html b/LayoutTests/fast/dom/element-attribute-js-null.html
index 850191ee6ff319863493a1f42de08753d5f9b443..aed6fc4cfa4506889da2386f5ed64147611018ef 100644
--- a/LayoutTests/fast/dom/element-attribute-js-null.html
+++ b/LayoutTests/fast/dom/element-attribute-js-null.html
@@ -365,7 +365,7 @@
                     elementToUse: document.createElement('label'),
                     attributes: [
                         {name: 'accessKey', expectedNull: ''},
-                        {name: 'htmlFor', expectedNull: ''}
+                        {name: 'htmlFor', expectedNull: 'null'}
                     ]
                 },
                 {
@@ -373,7 +373,7 @@
                     elementToUse: document.createElement('legend'),
                     attributes: [
                         {name: 'accessKey', expectedNull: ''},
-                        {name: 'align', expectedNull: ''}
+                        {name: 'align', expectedNull: 'null'}
                     ]
                 },
                 {
@@ -401,7 +401,7 @@
                     type: 'HTMLMapElement',
                     elementToUse: document.createElement('map'),
                     attributes: [
-                        {name: 'name', expectedNull: ''}
+                        {name: 'name', expectedNull: 'null'}
                     ]
                 },
 
@@ -456,7 +456,7 @@
                     type: 'HTMLOptGroupElement',
                     elementToUse: document.createElement('optgroup'),
                     attributes: [
-                        {name: 'label', expectedNull: ''}
+                        {name: 'label', expectedNull: 'null'}
                     ]
                 },
                 {
@@ -529,8 +529,8 @@
                     type: 'HTMLStyleElement',
                     elementToUse: document.createElement('style'),
                     attributes: [
-                        {name: 'media', expectedNull: ''},
-                        {name: 'type', expectedNull: ''}
+                        {name: 'media', expectedNull: 'null'},
+                        {name: 'type', expectedNull: 'null'}
                     ]
                 },
                 {
@@ -618,7 +618,7 @@
                     type: 'HTMLTitleElement',
                     elementToUse: document.createElement('title'),
                     attributes: [
-                        {name: 'text', expectedNull: ''}
+                        {name: 'text', expectedNull: 'null'}
                     ]
                 },
                 {