diff --git a/mozilla/content/base/public/nsINode.h b/mozilla/content/base/public/nsINode.h
index 30f74fcbe0d..87f7a3617f3 100644
--- a/mozilla/content/base/public/nsINode.h
+++ b/mozilla/content/base/public/nsINode.h
@@ -92,14 +92,8 @@ enum {
 
   NODE_IS_EDITABLE =             0x00000100U,
 
-  // Optimizations to quickly check whether element may have ID, class or style
-  // attributes. Not all element implementations may use these!
-  NODE_MAY_HAVE_ID =             0x00000200U,
-  NODE_MAY_HAVE_CLASS =          0x00000400U,
-  NODE_MAY_HAVE_STYLE =          0x00000800U,
-
   // Four bits for the script-type ID
-  NODE_SCRIPT_TYPE_OFFSET =               12,
+  NODE_SCRIPT_TYPE_OFFSET =                9,
 
   NODE_SCRIPT_TYPE_SIZE =                  4,
 
diff --git a/mozilla/content/base/src/nsGenericElement.cpp b/mozilla/content/base/src/nsGenericElement.cpp
index 852d189a400..b7f8ec68b04 100644
--- a/mozilla/content/base/src/nsGenericElement.cpp
+++ b/mozilla/content/base/src/nsGenericElement.cpp
@@ -2265,10 +2265,6 @@ nsGenericElement::DispatchDOMEvent(nsEvent* aEvent,
 nsIAtom*
 nsGenericElement::GetID() const
 {
-  if (!HasFlag(NODE_MAY_HAVE_ID)) {
-    return nsnull;
-  }
-
   nsIAtom* IDName = GetIDAttributeName();
   if (IDName) {
     const nsAttrValue* attrVal = mAttrsAndChildren.GetAttr(IDName);
@@ -2291,9 +2287,6 @@ nsGenericElement::GetID() const
       }
     }
   }
-
-  nsINode* node = const_cast<nsINode*>(static_cast<const nsINode*>(this));
-  node->UnsetFlags(NODE_MAY_HAVE_ID);
   return nsnull;
 }
 
@@ -3687,7 +3680,6 @@ nsGenericElement::ParseAttribute(PRInt32 aNamespaceID,
 {
   if (aNamespaceID == kNameSpaceID_None &&
       aAttribute == GetIDAttributeName() && !aValue.IsEmpty()) {
-    SetFlags(NODE_MAY_HAVE_ID);
     // Store id as an atom.  id="" means that the element has no id,
     // not that it has an emptystring as the id.
     aResult.ParseAtom(aValue);
diff --git a/mozilla/content/base/src/nsStyledElement.cpp b/mozilla/content/base/src/nsStyledElement.cpp
index 0967391c4f7..454fdbf7c9f 100644
--- a/mozilla/content/base/src/nsStyledElement.cpp
+++ b/mozilla/content/base/src/nsStyledElement.cpp
@@ -73,15 +73,7 @@ nsStyledElement::GetIDAttributeName() const
 const nsAttrValue*
 nsStyledElement::GetClasses() const
 {
-  if (!HasFlag(NODE_MAY_HAVE_CLASS)) {
-    return nsnull;
-  }
-  const nsAttrValue* clazz = mAttrsAndChildren.GetAttr(nsGkAtoms::_class);
-  if (!clazz) {
-    nsINode* node = const_cast<nsINode*>(static_cast<const nsINode*>(this));
-    node->UnsetFlags(NODE_MAY_HAVE_CLASS);
-  }
-  return clazz;
+  return mAttrsAndChildren.GetAttr(nsGkAtoms::_class);
 }
 
 PRBool
@@ -90,12 +82,10 @@ nsStyledElement::ParseAttribute(PRInt32 aNamespaceID, nsIAtom* aAttribute,
 {
   if (aNamespaceID == kNameSpaceID_None) {
     if (aAttribute == nsGkAtoms::style) {
-      SetFlags(NODE_MAY_HAVE_STYLE);
       ParseStyleAttribute(this, aValue, aResult);
       return PR_TRUE;
     }
     if (aAttribute == nsGkAtoms::_class) {
-      SetFlags(NODE_MAY_HAVE_CLASS);
 #ifdef MOZ_SVG
       NS_ASSERTION(!nsCOMPtr<nsIDOMSVGStylable>(do_QueryInterface(this)),
                    "SVG code should have handled this 'class' attribute!");
@@ -112,7 +102,6 @@ nsStyledElement::ParseAttribute(PRInt32 aNamespaceID, nsIAtom* aAttribute,
 NS_IMETHODIMP
 nsStyledElement::SetInlineStyleRule(nsICSSStyleRule* aStyleRule, PRBool aNotify)
 {
-  SetFlags(NODE_MAY_HAVE_STYLE);
   PRBool modification = PR_FALSE;
   nsAutoString oldValueStr;
 
@@ -146,16 +135,12 @@ nsStyledElement::SetInlineStyleRule(nsICSSStyleRule* aStyleRule, PRBool aNotify)
 nsICSSStyleRule*
 nsStyledElement::GetInlineStyleRule()
 {
-  if (!HasFlag(NODE_MAY_HAVE_STYLE)) {
-    return nsnull;
-  }
   const nsAttrValue* attrVal = mAttrsAndChildren.GetAttr(nsGkAtoms::style);
 
   if (attrVal && attrVal->Type() == nsAttrValue::eCSSStyleRule) {
     return attrVal->GetCSSStyleRuleValue();
   }
 
-  UnsetFlags(NODE_MAY_HAVE_STYLE);
   return nsnull;
 }
 
@@ -211,9 +196,6 @@ nsStyledElement::GetStyle(nsIDOMCSSStyleDeclaration** aStyle)
 nsresult
 nsStyledElement::ReparseStyleAttribute()
 {
-  if (!HasFlag(NODE_MAY_HAVE_STYLE)) {
-    return NS_OK;
-  }
   const nsAttrValue* oldVal = mAttrsAndChildren.GetAttr(nsGkAtoms::style);
   
   if (oldVal && oldVal->Type() != nsAttrValue::eCSSStyleRule) {