Use parseHTMLInteger for parsing minlength and maxlength in <textarea>

LayoutTests/fast/forms/textarea-maxlength.html

Index: LayoutTests/fast/forms/textarea-maxlength.html
diff --git a/LayoutTests/fast/forms/textarea-maxlength.html b/LayoutTests/fast/forms/textarea-maxlength.html
index 98d7fb50d033fb9028330bdea256f0a8c5af1909..d7be9ba0f295653f22ddec4dc9d20e55e1067531 100644
--- a/LayoutTests/fast/forms/textarea-maxlength.html
+++ b/LayoutTests/fast/forms/textarea-maxlength.html
@@ -21,6 +21,14 @@ shouldBe('textArea.maxLength', '-1');
 textArea.setAttribute('maxlength', 'xyz');
 shouldBe('textArea.maxLength', '-1');
 
+// Leading whitespaces in maxlength attributes
+textArea.setAttribute('maxlength', '\t  \n\r1');
+shouldBe('textArea.maxLength', '1');
+textArea.setAttribute('maxlength', "\u20021");
+shouldBe('textArea.maxLength', '-1');
+textArea.setAttribute('maxlength', "\u20091");
+shouldBe('textArea.maxLength', '-1');
+
 // Valid maxlength attributes
 textArea.setAttribute('maxlength', '1');
 shouldBe('textArea.maxLength', '1');