Fix bug where form/fieldset :valid/:invalid won't be recalculated upon control's willValidate change

LayoutTests/fast/forms/form-pseudo-valid-style-expected.txt

Index: LayoutTests/fast/forms/form-pseudo-valid-style-expected.txt
diff --git a/LayoutTests/fast/forms/form-pseudo-valid-style-expected.txt b/LayoutTests/fast/forms/form-pseudo-valid-style-expected.txt
index 69f791a535dc5b4e0581d4a54630291cb209c8bf..8d20ee73ee108ddaf5e87a52893351e9263c6ac2 100644
--- a/LayoutTests/fast/forms/form-pseudo-valid-style-expected.txt
+++ b/LayoutTests/fast/forms/form-pseudo-valid-style-expected.txt
@@ -3,7 +3,7 @@ Check if :valid/:invalid CSS pseudo selectors are lively applied for forms
 On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
 
 
-Removing and adding required text inputs and modifying ther value by a DOM tree mutation:
+Removing and adding required text inputs and modifying their value by a DOM tree mutation:
 PASS backgroundOf(form1) is invalidColor
 PASS backgroundOf(sub1) is subInvalidColor
 PASS form1.removeChild(input1); backgroundOf(form1) is validColor
@@ -15,6 +15,22 @@ PASS backgroundOf(sub1) is subValidColor
 PASS input2.setAttribute("value", ""); backgroundOf(form1) is invalidColor
 PASS backgroundOf(sub1) is subInvalidColor
 
+Disabling and marking inputs readonly by a DOM tree mutation:
+PASS backgroundOf(form1) is invalidColor
+PASS backgroundOf(sub1) is subInvalidColor
+PASS input1.disabled=1; backgroundOf(form1) is validColor
+PASS backgroundOf(sub1) is subValidColor
+PASS input1.disabled=0; backgroundOf(form1) is invalidColor
+PASS backgroundOf(sub1) is subInvalidColor
+PASS input1.setAttribute("readonly", "1"); backgroundOf(form1) is validColor
+PASS backgroundOf(sub1) is subValidColor
+
+Move element under datalist by a DOM tree mutation:
+PASS backgroundOf(form1) is invalidColor
+PASS parent.removeChild(input1); backgroundOf(form1) is validColor
+PASS dl1.appendChild(input1); backgroundOf(form1) is validColor
+PASS parent.appendChild(input1); backgroundOf(form1) is invalidColor
+
 Adding a required text input that is not a direct child of the form:
 PASS backgroundOf(form1) is validColor
 PASS div1.appendChild(input1); backgroundOf(form1) is invalidColor