diff --git a/content/html/content/src/nsHTMLOptionElement.cpp b/content/html/content/src/nsHTMLOptionElement.cpp
index 7b90633d748e..ddb7c92a4469 100644
--- a/content/html/content/src/nsHTMLOptionElement.cpp
+++ b/content/html/content/src/nsHTMLOptionElement.cpp
@@ -152,7 +152,7 @@ NS_NewHTMLOptionElement(nsINodeInfo *aNodeInfo, PRBool aFromParser)
     NS_ENSURE_TRUE(doc, nsnull);
 
     nodeInfo = doc->NodeInfoManager()->GetNodeInfo(nsGkAtoms::option, nsnull,
-                                                   kNameSpaceID_None);
+                                                   kNameSpaceID_XHTML);
     NS_ENSURE_TRUE(nodeInfo, nsnull);
   }
 
diff --git a/content/html/content/src/nsHTMLStyleElement.cpp b/content/html/content/src/nsHTMLStyleElement.cpp
index 8c624506962a..fd1b3bfab8d4 100644
--- a/content/html/content/src/nsHTMLStyleElement.cpp
+++ b/content/html/content/src/nsHTMLStyleElement.cpp
@@ -319,7 +319,8 @@ nsHTMLStyleElement::GetStyleSheetURL(PRBool* aIsInline,
   if (*aIsInline) {
     return;
   }
-  if (mNodeInfo->NamespaceEquals(kNameSpaceID_XHTML)) {
+  if (GetOwnerDoc() && // XXX clean up after bug 335998 lands
+      !(GetOwnerDoc()->IsCaseSensitive())) {
     // We stopped supporting <style src="..."> for XHTML as it is
     // non-standard.
     *aIsInline = PR_TRUE;
diff --git a/content/html/content/src/nsHTMLTableRowElement.cpp b/content/html/content/src/nsHTMLTableRowElement.cpp
index fe062246e1c0..8a78cdd4c8cf 100644
--- a/content/html/content/src/nsHTMLTableRowElement.cpp
+++ b/content/html/content/src/nsHTMLTableRowElement.cpp
@@ -250,7 +250,7 @@ nsHTMLTableRowElement::GetCells(nsIDOMHTMLCollection** aValue)
                                nsnull, // closure data
                                PR_FALSE,
                                nsnull,
-                               kNameSpaceID_None,
+                               kNameSpaceID_XHTML,
                                PR_FALSE);
 
     NS_ENSURE_TRUE(mCells, NS_ERROR_OUT_OF_MEMORY);
diff --git a/content/html/document/src/nsHTMLFragmentContentSink.cpp b/content/html/document/src/nsHTMLFragmentContentSink.cpp
index ab39244bbbc5..c8006546c3ca 100644
--- a/content/html/document/src/nsHTMLFragmentContentSink.cpp
+++ b/content/html/document/src/nsHTMLFragmentContentSink.cpp
@@ -419,7 +419,7 @@ nsHTMLFragmentContentSink::OpenContainer(const nsIParserNode& aNode)
       ToLowerCase(tmp);
 
       nsCOMPtr<nsIAtom> name = do_GetAtom(tmp);
-      nodeInfo = mNodeInfoManager->GetNodeInfo(name, nsnull, kNameSpaceID_None);
+      nodeInfo = mNodeInfoManager->GetNodeInfo(name, nsnull, kNameSpaceID_XHTML);
       NS_ENSURE_TRUE(nodeInfo, NS_ERROR_OUT_OF_MEMORY);
     }
     else if (mNodeInfoCache[nodeType]) {
@@ -433,7 +433,7 @@ nsHTMLFragmentContentSink::OpenContainer(const nsIParserNode& aNode)
       nsIAtom *name = parserService->HTMLIdToAtomTag(nodeType);
       NS_ASSERTION(name, "This should not happen!");
 
-      nodeInfo = mNodeInfoManager->GetNodeInfo(name, nsnull, kNameSpaceID_None);
+      nodeInfo = mNodeInfoManager->GetNodeInfo(name, nsnull, kNameSpaceID_XHTML);
       NS_ENSURE_TRUE(nodeInfo, NS_ERROR_OUT_OF_MEMORY);
 
       NS_ADDREF(mNodeInfoCache[nodeType] = nodeInfo);
@@ -521,7 +521,7 @@ nsHTMLFragmentContentSink::AddLeaf(const nsIParserNode& aNode)
 
           nsCOMPtr<nsIAtom> name = do_GetAtom(tmp);
           nodeInfo = mNodeInfoManager->GetNodeInfo(name, nsnull,
-                                                   kNameSpaceID_None);
+                                                   kNameSpaceID_XHTML);
           NS_ENSURE_TRUE(nodeInfo, NS_ERROR_OUT_OF_MEMORY);
         }
         else if (mNodeInfoCache[nodeType]) {
@@ -532,7 +532,7 @@ nsHTMLFragmentContentSink::AddLeaf(const nsIParserNode& aNode)
           NS_ASSERTION(name, "This should not happen!");
 
           nodeInfo = mNodeInfoManager->GetNodeInfo(name, nsnull,
-                                                   kNameSpaceID_None);
+                                                   kNameSpaceID_XHTML);
           NS_ENSURE_TRUE(nodeInfo, NS_ERROR_OUT_OF_MEMORY);
           NS_ADDREF(mNodeInfoCache[nodeType] = nodeInfo);
         }
@@ -1011,7 +1011,7 @@ nsHTMLParanoidFragmentSink::NameFromNode(const nsIParserNode& aNode,
     nsCOMPtr<nsINodeInfo> nodeInfo;
     rv =
       mNodeInfoManager->GetNodeInfo(aNode.GetText(), nsnull,
-                                    kNameSpaceID_None,
+                                    kNameSpaceID_XHTML,
                                     getter_AddRefs(nodeInfo));
     NS_ENSURE_SUCCESS(rv, rv);
     NS_IF_ADDREF(*aResult = nodeInfo->NameAtom());
diff --git a/content/html/document/src/nsImageDocument.cpp b/content/html/document/src/nsImageDocument.cpp
index 1927442849cd..c75a2a8fa7de 100644
--- a/content/html/document/src/nsImageDocument.cpp
+++ b/content/html/document/src/nsImageDocument.cpp
@@ -631,7 +631,7 @@ nsImageDocument::CreateSyntheticDocument()
 
   nsCOMPtr<nsINodeInfo> nodeInfo;
   nodeInfo = mNodeInfoManager->GetNodeInfo(nsGkAtoms::img, nsnull,
-                                           kNameSpaceID_None);
+                                           kNameSpaceID_XHTML);
   NS_ENSURE_TRUE(nodeInfo, NS_ERROR_OUT_OF_MEMORY);
 
   mImageContent = NS_NewHTMLImageElement(nodeInfo);
diff --git a/content/html/document/src/nsMediaDocument.cpp b/content/html/document/src/nsMediaDocument.cpp
index dc688c763f2c..6c9333f21525 100644
--- a/content/html/document/src/nsMediaDocument.cpp
+++ b/content/html/document/src/nsMediaDocument.cpp
@@ -234,7 +234,7 @@ nsMediaDocument::CreateSyntheticDocument()
 
   nsCOMPtr<nsINodeInfo> nodeInfo;
   nodeInfo = mNodeInfoManager->GetNodeInfo(nsGkAtoms::html, nsnull,
-                                           kNameSpaceID_None);
+                                           kNameSpaceID_XHTML);
   NS_ENSURE_TRUE(nodeInfo, NS_ERROR_OUT_OF_MEMORY);
 
   nsRefPtr<nsGenericHTMLElement> root = NS_NewHTMLHtmlElement(nodeInfo);
@@ -247,7 +247,7 @@ nsMediaDocument::CreateSyntheticDocument()
   NS_ENSURE_SUCCESS(rv, rv);
 
   nodeInfo = mNodeInfoManager->GetNodeInfo(nsGkAtoms::head, nsnull,
-                                           kNameSpaceID_None);
+                                           kNameSpaceID_XHTML);
   NS_ENSURE_TRUE(nodeInfo, NS_ERROR_OUT_OF_MEMORY);
 
   // Create a <head> so our title has somewhere to live
@@ -259,7 +259,7 @@ nsMediaDocument::CreateSyntheticDocument()
   root->AppendChildTo(head, PR_FALSE);
 
   nodeInfo = mNodeInfoManager->GetNodeInfo(nsGkAtoms::body, nsnull,
-                                           kNameSpaceID_None);
+                                           kNameSpaceID_XHTML);
   NS_ENSURE_TRUE(nodeInfo, NS_ERROR_OUT_OF_MEMORY);
 
   nsRefPtr<nsGenericHTMLElement> body = NS_NewHTMLBodyElement(nodeInfo);
diff --git a/content/html/document/src/nsVideoDocument.cpp b/content/html/document/src/nsVideoDocument.cpp
index 7ba47c8e8fe1..45f4460eae36 100644
--- a/content/html/document/src/nsVideoDocument.cpp
+++ b/content/html/document/src/nsVideoDocument.cpp
@@ -108,7 +108,7 @@ nsVideoDocument::CreateSyntheticVideoDocument(nsIChannel* aChannel,
   // make content
   nsCOMPtr<nsINodeInfo> nodeInfo;
   nodeInfo = mNodeInfoManager->GetNodeInfo(nsGkAtoms::video, nsnull,
-                                           kNameSpaceID_None);
+                                           kNameSpaceID_XHTML);
   NS_ENSURE_TRUE(nodeInfo, NS_ERROR_FAILURE);
 
   nsRefPtr<nsHTMLMediaElement> element =
diff --git a/content/xslt/src/xslt/txMozillaXMLOutput.cpp b/content/xslt/src/xslt/txMozillaXMLOutput.cpp
index a6a1e59dc656..5026e7d1dac4 100644
--- a/content/xslt/src/xslt/txMozillaXMLOutput.cpp
+++ b/content/xslt/src/xslt/txMozillaXMLOutput.cpp
@@ -453,11 +453,10 @@ txMozillaXMLOutput::startElement(nsIAtom* aPrefix, nsIAtom* aLocalName,
 
             aLowercaseLocalName = owner;
         }
-        return startElementInternal(nsnull, aLowercaseLocalName,
-                                    kNameSpaceID_None, kNameSpaceID_XHTML);
+        return startElementInternal(nsnull, aLowercaseLocalName, kNameSpaceID_XHTML);
     }
 
-    return startElementInternal(aPrefix, aLocalName, aNsID, aNsID);
+    return startElementInternal(aPrefix, aLocalName, aNsID);
 }
 
 nsresult
@@ -465,11 +464,11 @@ txMozillaXMLOutput::startElement(nsIAtom* aPrefix,
                                  const nsSubstring& aLocalName,
                                  const PRInt32 aNsID)
 {
-    PRInt32 elemType = aNsID;
+    PRInt32 nsId = aNsID;
     nsCOMPtr<nsIAtom> lname;
 
     if (mOutputFormat.mMethod == eHTMLOutput && aNsID == kNameSpaceID_None) {
-        elemType = kNameSpaceID_XHTML;
+        nsId = kNameSpaceID_XHTML;
 
         nsAutoString lnameStr;
         ToLowerCase(aLocalName, lnameStr);
@@ -483,22 +482,21 @@ txMozillaXMLOutput::startElement(nsIAtom* aPrefix,
     NS_ENSURE_TRUE(lname, NS_ERROR_OUT_OF_MEMORY);
 
     // Check that it's a valid name
-    if (!nsContentUtils::IsValidNodeName(lname, aPrefix, aNsID)) {
+    if (!nsContentUtils::IsValidNodeName(lname, aPrefix, nsId)) {
         // Try without prefix
         aPrefix = nsnull;
-        if (!nsContentUtils::IsValidNodeName(lname, aPrefix, aNsID)) {
+        if (!nsContentUtils::IsValidNodeName(lname, aPrefix, nsId)) {
             return NS_ERROR_XSLT_BAD_NODE_NAME;
         }
     }
 
-    return startElementInternal(aPrefix, lname, aNsID, elemType);
+    return startElementInternal(aPrefix, lname, nsId);
 }
 
 nsresult
 txMozillaXMLOutput::startElementInternal(nsIAtom* aPrefix,
                                          nsIAtom* aLocalName,
-                                         PRInt32 aNsID,
-                                         PRInt32 aElemType)
+                                         PRInt32 aNsID)
 {
     TX_ENSURE_CURRENTNODE;
 
@@ -539,12 +537,12 @@ txMozillaXMLOutput::startElementInternal(nsIAtom* aPrefix,
     ni = mNodeInfoManager->GetNodeInfo(aLocalName, aPrefix, aNsID);
     NS_ENSURE_TRUE(ni, NS_ERROR_OUT_OF_MEMORY);
 
-    NS_NewElement(getter_AddRefs(mOpenedElement), aElemType, ni, PR_FALSE);
+    NS_NewElement(getter_AddRefs(mOpenedElement), aNsID, ni, PR_FALSE);
 
     // Set up the element and adjust state
     if (!mNoFixup) {
-        if (aElemType == kNameSpaceID_XHTML) {
-            mOpenedElementIsHTML = aNsID != kNameSpaceID_XHTML;
+        if (aNsID == kNameSpaceID_XHTML) {
+            mOpenedElementIsHTML = (mOutputFormat.mMethod == eHTMLOutput);
             rv = startHTMLElement(mOpenedElement, mOpenedElementIsHTML);
             NS_ENSURE_SUCCESS(rv, rv);
 
diff --git a/content/xslt/src/xslt/txMozillaXMLOutput.h b/content/xslt/src/xslt/txMozillaXMLOutput.h
index fb93bfbbec3f..99bfbc63ffd1 100644
--- a/content/xslt/src/xslt/txMozillaXMLOutput.h
+++ b/content/xslt/src/xslt/txMozillaXMLOutput.h
@@ -121,7 +121,7 @@ private:
     nsresult attributeInternal(nsIAtom* aPrefix, nsIAtom* aLocalName,
                                PRInt32 aNsID, const nsString& aValue);
     nsresult startElementInternal(nsIAtom* aPrefix, nsIAtom* aLocalName,
-                                  PRInt32 aNsID, PRInt32 aElemType);
+                                  PRInt32 aNsID);
 
     nsCOMPtr<nsIDocument> mDocument;
     nsCOMPtr<nsINode> mCurrentNode;     // This is updated once an element is
diff --git a/content/xslt/src/xslt/txUnknownHandler.cpp b/content/xslt/src/xslt/txUnknownHandler.cpp
index bc43293ea02d..64e7e675df42 100644
--- a/content/xslt/src/xslt/txUnknownHandler.cpp
+++ b/content/xslt/src/xslt/txUnknownHandler.cpp
@@ -93,7 +93,7 @@ txUnknownHandler::startElement(nsIAtom* aPrefix, nsIAtom* aLocalName,
         aLowercaseLocalName = owner;
     }
 
-    PRBool htmlRoot = aNsID == kNameSpaceID_None && !aPrefix &&
+    PRBool htmlRoot = aNsID == kNameSpaceID_XHTML && !aPrefix &&
                       aLowercaseLocalName == txHTMLAtoms::html;
 
     // Use aLocalName and not aLowercaseLocalName in case the output
diff --git a/layout/build/nsContentDLF.cpp b/layout/build/nsContentDLF.cpp
index 3f05e24d1c50..e7467dbb7c31 100644
--- a/layout/build/nsContentDLF.cpp
+++ b/layout/build/nsContentDLF.cpp
@@ -361,15 +361,15 @@ nsContentDLF::CreateBlankDocument(nsILoadGroup *aLoadGroup,
     nsCOMPtr<nsINodeInfo> htmlNodeInfo;
 
     // generate an html html element
-    htmlNodeInfo = nim->GetNodeInfo(nsGkAtoms::html, 0, kNameSpaceID_None);
+    htmlNodeInfo = nim->GetNodeInfo(nsGkAtoms::html, 0, kNameSpaceID_XHTML);
     nsCOMPtr<nsIContent> htmlElement = NS_NewHTMLHtmlElement(htmlNodeInfo);
 
     // generate an html head element
-    htmlNodeInfo = nim->GetNodeInfo(nsGkAtoms::head, 0, kNameSpaceID_None);
+    htmlNodeInfo = nim->GetNodeInfo(nsGkAtoms::head, 0, kNameSpaceID_XHTML);
     nsCOMPtr<nsIContent> headElement = NS_NewHTMLHeadElement(htmlNodeInfo);
 
     // generate an html body element
-    htmlNodeInfo = nim->GetNodeInfo(nsGkAtoms::body, 0, kNameSpaceID_None);
+    htmlNodeInfo = nim->GetNodeInfo(nsGkAtoms::body, 0, kNameSpaceID_XHTML);
     nsCOMPtr<nsIContent> bodyElement = NS_NewHTMLBodyElement(htmlNodeInfo);
 
     // blat in the structure
diff --git a/layout/generic/nsObjectFrame.cpp b/layout/generic/nsObjectFrame.cpp
index 82d95ee0bcd3..03657572e4df 100644
--- a/layout/generic/nsObjectFrame.cpp
+++ b/layout/generic/nsObjectFrame.cpp
@@ -3057,21 +3057,10 @@ nsresult nsPluginInstanceOwner::EnsureCachedAttrParamArrays()
   // might kill us...
   nsCOMPtr<nsIPluginInstanceOwner> kungFuDeathGrip(this);
   
-  if (ni->NamespaceEquals(kNameSpaceID_XHTML)) {
-    // For XHTML elements we need to take the namespace URI into
-    // account when looking for param elements.
+  NS_NAMED_LITERAL_STRING(xhtml_ns, "http://www.w3.org/1999/xhtml");
 
-    NS_NAMED_LITERAL_STRING(xhtml_ns, "http://www.w3.org/1999/xhtml");
-
-    mydomElement->GetElementsByTagNameNS(xhtml_ns, NS_LITERAL_STRING("param"),
-                                         getter_AddRefs(allParams));
-  } else {
-    // If content is not XHTML, it must be HTML, no need to worry
-    // about namespaces then...
-
-    mydomElement->GetElementsByTagName(NS_LITERAL_STRING("param"),
+  mydomElement->GetElementsByTagNameNS(xhtml_ns, NS_LITERAL_STRING("param"),
                                        getter_AddRefs(allParams));
-  }    
 
   if (allParams) {
     PRUint32 numAllParams; 
@@ -3162,7 +3151,8 @@ nsresult nsPluginInstanceOwner::EnsureCachedAttrParamArrays()
   // (see the AddAttributes functions in the HTML and XML content sinks).
   PRInt16 start, end, increment;
   if (mContent->IsNodeOfType(nsINode::eHTML) &&
-      mContent->NodeInfo()->NamespaceEquals(kNameSpaceID_None)) {
+      mContent->GetOwnerDoc() && // XXX clean up after bug 335998 lands
+      !(mContent->GetOwnerDoc()->IsCaseSensitive())) {
     // HTML.  Walk attributes in reverse order.
     start = numRealAttrs - 1;
     end = -1;
diff --git a/layout/html/tests/TestAttributes.cpp b/layout/html/tests/TestAttributes.cpp
index 5b9c89102e5e..d5d0765ee59b 100644
--- a/layout/html/tests/TestAttributes.cpp
+++ b/layout/html/tests/TestAttributes.cpp
@@ -291,7 +291,7 @@ int main(int argc, char** argv)
   nsIAtom* li = NS_NewAtom("li");
 
   nsCOMPtr<nsINodeInfo> ni;
-  myDoc->NodeInfoManager()->GetNodeInfo(li, nsnull, kNameSpaceID_None,
+  myDoc->NodeInfoManager()->GetNodeInfo(li, nsnull, kNameSpaceID_XHTML,
                                         getter_AddRefs(ni));
 
   rv = NS_NewHTMLLIElement(&container,ni);
diff --git a/layout/style/nsCSSRuleProcessor.cpp b/layout/style/nsCSSRuleProcessor.cpp
index d67cb5005de4..92d1ad8011ca 100644
--- a/layout/style/nsCSSRuleProcessor.cpp
+++ b/layout/style/nsCSSRuleProcessor.cpp
@@ -900,13 +900,10 @@ RuleProcessorData::RuleProcessorData(nsPresContext* aPresContext,
     // check for HTMLContent and Link status
     if (aContent->IsNodeOfType(nsINode::eHTML)) {
       mIsHTMLContent = PR_TRUE;
-      // Note that we want to treat non-XML HTML content as XHTML for namespace
-      // purposes, since html.css has that namespace declared.
-      mNameSpaceID = kNameSpaceID_XHTML;
-    } else {
-      // get the namespace
-      mNameSpaceID = aContent->GetNameSpaceID();
     }
+    
+    // get the namespace
+    mNameSpaceID = aContent->GetNameSpaceID();
 
     // if HTML content and it has some attributes, check for an HTML link
     // NOTE: optimization: cannot be a link if no attributes (since it needs an href)
@@ -1571,7 +1568,8 @@ static PRBool SelectorMatches(RuleProcessorData &data,
     }
     else if (nsCSSPseudoClasses::mozIsHTML == pseudoClass->mAtom) {
       result = data.mIsHTMLContent &&
-        data.mContent->GetNameSpaceID() == kNameSpaceID_None;
+        data.mContent->GetOwnerDoc() && // XXX clean up after bug 335998 lands
+        !(data.mContent->GetOwnerDoc()->IsCaseSensitive());
     }
 #ifdef MOZ_MATHML
     else if (nsCSSPseudoClasses::mozMathIncrementScriptLevel == pseudoClass->mAtom) {