diff --git a/content/base/src/nsGkAtomList.h b/content/base/src/nsGkAtomList.h
index 370d251aa769..aa2161d64849 100755
--- a/content/base/src/nsGkAtomList.h
+++ b/content/base/src/nsGkAtomList.h
@@ -85,6 +85,7 @@ GK_ATOM(allowevents, "allowevents")
 GK_ATOM(allownegativeassertions, "allownegativeassertions")
 GK_ATOM(allowuntrusted, "allowuntrusted")
 GK_ATOM(alt, "alt")
+GK_ATOM(alternate, "alternate")
 GK_ATOM(always, "always")
 GK_ATOM(ancestor, "ancestor")
 GK_ATOM(ancestorOrSelf, "ancestor-or-self")
diff --git a/content/base/src/nsParserUtils.cpp b/content/base/src/nsParserUtils.cpp
index 802f81bc9212..8b79634f7ccd 100644
--- a/content/base/src/nsParserUtils.cpp
+++ b/content/base/src/nsParserUtils.cpp
@@ -40,6 +40,8 @@
 #include "jsapi.h"
 #include "nsReadableUtils.h"
 #include "nsCRT.h"
+#include "nsContentUtils.h"
+#include "nsIParserService.h"
 
 #define SKIP_WHITESPACE(iter, end_iter)                          \
   while ((iter) != (end_iter) && nsCRT::IsAsciiSpace(*(iter))) { \
@@ -57,16 +59,14 @@
     break
 
 PRBool
-nsParserUtils::GetQuotedAttributeValue(const nsAString& aSource,
-                                       const nsAString& aAttribute,
+nsParserUtils::GetQuotedAttributeValue(const nsString& aSource, nsIAtom *aName,
                                        nsAString& aValue)
 {
-  NS_ASSERTION(!aAttribute.IsEmpty(), "Empty attribute name cannot be searched for usefully");
   aValue.Truncate();
-  nsAString::const_iterator start, end;
-  aSource.BeginReading(start);
-  aSource.EndReading(end);
-  nsAString::const_iterator iter;
+
+  const PRUnichar *start = aSource.get();
+  const PRUnichar *end = start + aSource.Length();
+  const PRUnichar *iter;
   
   while (start != end) {
     SKIP_WHITESPACE(start, end);
@@ -74,7 +74,7 @@ nsParserUtils::GetQuotedAttributeValue(const nsAString& aSource,
     SKIP_ATTR_NAME(iter, end);
 
     // Remember the attr name.
-    const nsAString & attrName = Substring(start, iter);
+    const nsDependentSubstring & attrName = Substring(start, iter);
 
     // Now check whether this is a valid name="value" pair.
     start = iter;
@@ -96,23 +96,60 @@ nsParserUtils::GetQuotedAttributeValue(const nsAString& aSource,
     
     ++start;  // Point to the first char of the value.
     iter = start;
-    if (!FindCharInReadable(q, iter, end)) {
+
+    while (iter != end && *iter != q) {
+      ++iter;
+    }
+
+    if (iter == end) {
       // Oops, unterminated quoted string.
       break;
     }
-    
+
     // At this point attrName holds the name of the "attribute" and
     // the value is between start and iter.
     
-    if (!attrName.Equals(aAttribute)) {
-      // Resume scanning after the end of the attribute value.
-      start = iter;
-      ++start;  // To move past the quote char.
-      continue;
+    if (aName->Equals(attrName)) {
+      nsAString::iterator dest;
+      aValue.BeginWriting(dest);
+
+      while (start != iter) {
+        if (*start == kLessThan) {
+          return PR_FALSE;
+        }
+
+        if (*start == kAmpersand) {
+          nsIParserService* parserService = nsContentUtils::GetParserService();
+          NS_ENSURE_TRUE(parserService, PR_FALSE);
+
+          const PRUnichar *pos = start;
+
+          // Point to first character after the ampersand.
+          ++start;
+
+          // We rely on the fact that if this is a valid character reference,
+          // dest will be a buffer with at least two PRUnichars (starting with
+          // &#), so enough to contain any UTF-16 character.
+          PRUint32 count =
+            parserService->DecodeEntity(start, iter, &pos, dest.get());
+          NS_ENSURE_TRUE(count > 0, PR_FALSE);
+
+          start = pos;
+          dest.advance(count);
+        }
+        else {
+          *dest = *start;
+          ++start;
+          ++dest;
+        }
+      }
+
+      return PR_TRUE;
     }
 
-    aValue = Substring(start, iter);
-    return PR_TRUE;
+    // Resume scanning after the end of the attribute value.
+    start = iter;
+    ++start;  // To move past the quote char.
   }
 
   return PR_FALSE;
diff --git a/content/base/src/nsParserUtils.h b/content/base/src/nsParserUtils.h
index 4f8228389c77..a2dfbd9d29e2 100644
--- a/content/base/src/nsParserUtils.h
+++ b/content/base/src/nsParserUtils.h
@@ -39,12 +39,23 @@
 #define nsParserUtils_h__
 
 #include "nsString.h"
+class nsIAtom;
 
 class nsParserUtils {
 public:
+  /**
+   * This will parse aSource, to extract the value of the pseudo attribute
+   * with the name specified in aName. See
+   * http://www.w3.org/TR/xml-stylesheet/#NT-StyleSheetPI for the specification
+   * which is used to parse aSource.
+   *
+   * @param aSource the string to parse
+   * @param aName the name of the attribute to get the value for
+   * @param aValue [out] the value for the attribute with name specified in
+   *                     aAttribute. Empty if the attribute isn't present.
+   */
   static PRBool
-  GetQuotedAttributeValue(const nsAString& aSource,
-                          const nsAString& aAttribute,
+  GetQuotedAttributeValue(const nsString& aSource, nsIAtom *aName,
                           nsAString& aValue);
 
   static PRBool
diff --git a/content/xml/content/src/nsXMLProcessingInstruction.cpp b/content/xml/content/src/nsXMLProcessingInstruction.cpp
index 800ef59652e7..4ae05c2012f5 100644
--- a/content/xml/content/src/nsXMLProcessingInstruction.cpp
+++ b/content/xml/content/src/nsXMLProcessingInstruction.cpp
@@ -122,13 +122,12 @@ nsXMLProcessingInstruction::GetData(nsAString& aData)
 }
 
 PRBool
-nsXMLProcessingInstruction::GetAttrValue(const nsAString& aAttr,
-                                         nsAString& aValue)
+nsXMLProcessingInstruction::GetAttrValue(nsIAtom *aName, nsAString& aValue)
 {
   nsAutoString data;
 
   GetData(data);
-  return nsParserUtils::GetQuotedAttributeValue(data, aAttr, aValue);
+  return nsParserUtils::GetQuotedAttributeValue(data, aName, aValue);
 }
 
 PRBool
diff --git a/content/xml/content/src/nsXMLProcessingInstruction.h b/content/xml/content/src/nsXMLProcessingInstruction.h
index 22c95ed42987..61e64b907ac8 100644
--- a/content/xml/content/src/nsXMLProcessingInstruction.h
+++ b/content/xml/content/src/nsXMLProcessingInstruction.h
@@ -73,7 +73,17 @@ public:
 #endif
 
 protected:
-  PRBool GetAttrValue(const nsAString& aAttr, nsAString& aValue);
+  /**
+   * This will parse the content of the PI, to extract the value of the pseudo
+   * attribute with the name specified in aName. See
+   * http://www.w3.org/TR/xml-stylesheet/#NT-StyleSheetPI for the specification
+   * which is used to parse the content of the PI.
+   *
+   * @param aName the name of the attribute to get the value for
+   * @param aValue [out] the value for the attribute with name specified in
+   *                     aAttribute. Empty if the attribute isn't present.
+   */
+  PRBool GetAttrValue(nsIAtom *aName, nsAString& aValue);
 
   nsAutoString mTarget;
 };
diff --git a/content/xml/content/src/nsXMLStylesheetPI.cpp b/content/xml/content/src/nsXMLStylesheetPI.cpp
index 1cec89e4fe6d..d557219a1a9a 100644
--- a/content/xml/content/src/nsXMLStylesheetPI.cpp
+++ b/content/xml/content/src/nsXMLStylesheetPI.cpp
@@ -148,11 +148,7 @@ nsXMLStylesheetPI::SetNodeValue(const nsAString& aNodeValue)
 NS_IMETHODIMP
 nsXMLStylesheetPI::GetCharset(nsAString& aCharset)
 {
-  if (!GetAttrValue(NS_LITERAL_STRING("charset"), aCharset)) {
-    return NS_ERROR_FAILURE;
-  }
-
-  return NS_OK;
+  return GetAttrValue(nsGkAtoms::charset, aCharset) ? NS_OK : NS_ERROR_FAILURE;
 }
 
 void
@@ -163,7 +159,7 @@ nsXMLStylesheetPI::GetStyleSheetURL(PRBool* aIsInline,
   *aURI = nsnull;
 
   nsAutoString href;
-  GetAttrValue(NS_LITERAL_STRING("href"), href);
+  GetAttrValue(nsGkAtoms::href, href);
   if (href.IsEmpty()) {
     return;
   }
@@ -197,31 +193,29 @@ nsXMLStylesheetPI::GetStyleSheetInfo(nsAString& aTitle,
     return;
   }
 
-  nsAutoString title, type, media, alternate;
+  nsAutoString data;
+  GetData(data);
 
-  GetAttrValue(NS_LITERAL_STRING("title"), title);
-  title.CompressWhitespace();
-  aTitle.Assign(title);
+  nsParserUtils::GetQuotedAttributeValue(data, nsGkAtoms::title, aTitle);
 
-  GetAttrValue(NS_LITERAL_STRING("alternate"), alternate);
+  nsAutoString alternate;
+  nsParserUtils::GetQuotedAttributeValue(data, nsGkAtoms::alternate, alternate);
 
   // if alternate, does it have title?
   if (alternate.EqualsLiteral("yes")) {
     if (aTitle.IsEmpty()) { // alternates must have title
       return;
-    } else {
-      *aIsAlternate = PR_TRUE;
     }
+
+    *aIsAlternate = PR_TRUE;
   }
 
-  GetAttrValue(NS_LITERAL_STRING("media"), media);
-  aMedia.Assign(media);
-  ToLowerCase(aMedia); // case sensitivity?
+  nsParserUtils::GetQuotedAttributeValue(data, nsGkAtoms::media, aMedia);
 
-  GetAttrValue(NS_LITERAL_STRING("type"), type);
+  nsAutoString type;
+  nsParserUtils::GetQuotedAttributeValue(data, nsGkAtoms::type, type);
 
-  nsAutoString mimeType;
-  nsAutoString notUsed;
+  nsAutoString mimeType, notUsed;
   nsParserUtils::SplitMimeType(type, mimeType, notUsed);
   if (!mimeType.IsEmpty() && !mimeType.LowerCaseEqualsLiteral("text/css")) {
     aType.Assign(type);
diff --git a/content/xml/document/src/nsXMLContentSink.cpp b/content/xml/document/src/nsXMLContentSink.cpp
index 8b7b8b47f82c..36545931fb6a 100644
--- a/content/xml/document/src/nsXMLContentSink.cpp
+++ b/content/xml/document/src/nsXMLContentSink.cpp
@@ -1133,64 +1133,80 @@ nsXMLContentSink::HandleProcessingInstruction(const PRUnichar *aTarget,
 {
   FlushText();
 
-  nsresult result = NS_OK;
   const nsDependentString target(aTarget);
   const nsDependentString data(aData);
 
   nsCOMPtr<nsIContent> node;
 
-  result = NS_NewXMLProcessingInstruction(getter_AddRefs(node),
-                                          mNodeInfoManager, target, data);
-  if (NS_OK == result) {
-    nsCOMPtr<nsIStyleSheetLinkingElement> ssle(do_QueryInterface(node));
+  nsresult rv = NS_NewXMLProcessingInstruction(getter_AddRefs(node),
+                                               mNodeInfoManager, target, data);
+  NS_ENSURE_SUCCESS(rv, rv);
 
-    if (ssle) {
-      ssle->InitStyleLinkElement(mParser, PR_FALSE);
-      ssle->SetEnableUpdates(PR_FALSE);
-      mPrettyPrintXML = PR_FALSE;
-    }
+  nsCOMPtr<nsIStyleSheetLinkingElement> ssle(do_QueryInterface(node));
+  if (ssle) {
+    ssle->InitStyleLinkElement(mParser, PR_FALSE);
+    ssle->SetEnableUpdates(PR_FALSE);
+    mPrettyPrintXML = PR_FALSE;
+  }
 
-    result = AddContentAsLeaf(node);
+  rv = AddContentAsLeaf(node);
+  NS_ENSURE_SUCCESS(rv, rv);
 
-    if (ssle) {
-      ssle->SetEnableUpdates(PR_TRUE);
-      result = ssle->UpdateStyleSheet(nsnull, nsnull);
+  if (ssle) {
+    ssle->SetEnableUpdates(PR_TRUE);
+    rv = ssle->UpdateStyleSheet(nsnull, nsnull);
 
-      if (NS_FAILED(result)) {
-        if (result == NS_ERROR_HTMLPARSER_BLOCK && mParser) {
-          mParser->BlockParser();
-        }
-        return result;
+    if (NS_FAILED(rv)) {
+      if (rv == NS_ERROR_HTMLPARSER_BLOCK && mParser) {
+        mParser->BlockParser();
       }
-    }
-
-    // If it's not a CSS stylesheet PI...
-    nsAutoString type;
-    nsParserUtils::GetQuotedAttributeValue(data, NS_LITERAL_STRING("type"), type);
-    if (mState == eXMLContentSinkState_InProlog && 
-        target.EqualsLiteral("xml-stylesheet") && 
-        !type.LowerCaseEqualsLiteral("text/css")) {
-      nsAutoString href, title, media, alternate;
-
-      nsParserUtils::GetQuotedAttributeValue(data, NS_LITERAL_STRING("href"), href);
-      // If there was no href, we can't do anything with this PI
-      if (href.IsEmpty()) {
-        return NS_OK;
-      }
-
-      nsParserUtils::GetQuotedAttributeValue(data, NS_LITERAL_STRING("title"), title);
-      title.CompressWhitespace();
-
-      nsParserUtils::GetQuotedAttributeValue(data, NS_LITERAL_STRING("media"), media);
-      ToLowerCase(media);
-
-      nsParserUtils::GetQuotedAttributeValue(data, NS_LITERAL_STRING("alternate"), alternate);
-
-      result = ProcessStyleLink(node, href, alternate.EqualsLiteral("yes"),
-                                title, type, media);
+      return rv;
     }
   }
-  return result;
+
+  // If it's not a CSS stylesheet PI...
+  nsAutoString type;
+  nsParserUtils::GetQuotedAttributeValue(data, nsGkAtoms::type, type);
+
+  if (mState != eXMLContentSinkState_InProlog ||
+      !target.EqualsLiteral("xml-stylesheet") ||
+      type.LowerCaseEqualsLiteral("text/css")) {
+    return NS_OK;
+  }
+
+  nsAutoString href, title, media;
+  PRBool isAlternate = PR_FALSE;
+  ParsePIData(data, href, title, media, isAlternate);
+
+  // If there was no href, we can't do anything with this PI
+  if (href.IsEmpty()) {
+      return NS_OK;
+  }
+
+  return ProcessStyleLink(node, href, isAlternate, title, type, media);
+}
+
+/* static */
+void
+nsXMLContentSink::ParsePIData(const nsString &aData, nsString &aHref,
+                              nsString &aTitle, nsString &aMedia,
+                              PRBool &aIsAlternate)
+{
+  nsParserUtils::GetQuotedAttributeValue(aData, nsGkAtoms::href, aHref);
+
+  // If there was no href, we can't do anything with this PI
+  if (aHref.IsEmpty()) {
+    return;
+  }
+
+  nsParserUtils::GetQuotedAttributeValue(aData, nsGkAtoms::title, aTitle);
+
+  nsParserUtils::GetQuotedAttributeValue(aData, nsGkAtoms::media, aMedia);
+
+  nsAutoString alternate;
+  nsParserUtils::GetQuotedAttributeValue(aData, nsGkAtoms::alternate, alternate);
+
+  aIsAlternate = alternate.EqualsLiteral("yes");
 }
 
 NS_IMETHODIMP
diff --git a/content/xml/document/src/nsXMLContentSink.h b/content/xml/document/src/nsXMLContentSink.h
index 8f0be02cedaf..5398d796b0d0 100644
--- a/content/xml/document/src/nsXMLContentSink.h
+++ b/content/xml/document/src/nsXMLContentSink.h
@@ -92,6 +92,10 @@ public:
   NS_IMETHOD OnDocumentCreated(nsIDOMDocument *aResultDocument);
   NS_IMETHOD OnTransformDone(nsresult aResult, nsIDOMDocument *aResultDocument);
 
+  static void ParsePIData(const nsString &aData, nsString &aHref,
+                          nsString &aTitle, nsString &aMedia,
+                          PRBool &aIsAlternate);
+
 protected:
   void StartLayout();
 
diff --git a/content/xul/document/src/nsXULContentSink.cpp b/content/xul/document/src/nsXULContentSink.cpp
index 033804cf1913..0b602dbebcff 100644
--- a/content/xul/document/src/nsXULContentSink.cpp
+++ b/content/xul/document/src/nsXULContentSink.cpp
@@ -903,10 +903,11 @@ XULContentSinkImpl::HandleProcessingInstruction(const PRUnichar *aTarget,
 
     tmp = targetStart;
 
+    nsresult rv;
     if (FindInReadable(NS_LITERAL_STRING("xul-overlay"), targetStart, targetEnd)) {
       // Load a XUL overlay.
       nsAutoString href;
-      nsParserUtils::GetQuotedAttributeValue(data, NS_LITERAL_STRING("href"), href);
+      nsParserUtils::GetQuotedAttributeValue(data, nsGkAtoms::href, href);
 
       // If there was no href, we can't do
       // anything with this PI
@@ -916,7 +917,7 @@ XULContentSinkImpl::HandleProcessingInstruction(const PRUnichar *aTarget,
 
       // Add the overlay to our list of overlays that need to be processed.
       nsCOMPtr<nsIURI> url;
-      nsresult rv = NS_NewURI(getter_AddRefs(url), href, nsnull, mDocumentURL);
+      rv = NS_NewURI(getter_AddRefs(url), href, nsnull, mDocumentURL);
       if (NS_FAILED(rv)) {
         // XXX This is wrong, the error message could be out of memory
         //     or something else equally bad, which we should propagate. 
@@ -924,50 +925,35 @@ XULContentSinkImpl::HandleProcessingInstruction(const PRUnichar *aTarget,
         return NS_OK; // The URL is bad, move along. Don't propagate for now.
       }
 
-      rv = mPrototype->AddOverlayReference(url);
-      if (NS_FAILED(rv)) return rv;
-    }
-    // If it's a stylesheet PI...
-    else {
-      targetStart = tmp;
-      if (FindInReadable(NS_LITERAL_STRING("xml-stylesheet"), targetStart, targetEnd)) {
-        nsAutoString href;
-        nsParserUtils::GetQuotedAttributeValue(data, NS_LITERAL_STRING("href"), href);
-
-        // If there was no href, we can't do
-        // anything with this PI
-        if (href.IsEmpty())
-            return NS_OK;
-
-        nsAutoString type;
-        nsParserUtils::GetQuotedAttributeValue(data, NS_LITERAL_STRING("type"), type);
-
-        nsAutoString title;
-        nsParserUtils::GetQuotedAttributeValue(data, NS_LITERAL_STRING("title"), title);
-
-        title.CompressWhitespace();
-
-        nsAutoString media;
-        nsParserUtils::GetQuotedAttributeValue(data, NS_LITERAL_STRING("media"), media);
-
-        ToLowerCase(media);
-
-        nsAutoString alternate;
-        nsParserUtils::GetQuotedAttributeValue(data, NS_LITERAL_STRING("alternate"), alternate);
-
-        nsresult result =  ProcessStyleLink(nsnull /* XXX need a node here */,
-                                            href, alternate.EqualsLiteral("yes"),  /* XXX ignore case? */
-                                            title, type, media);
-        if (NS_FAILED(result)) {
-          if (result == NS_ERROR_HTMLPARSER_BLOCK && mParser) {
-            mParser->BlockParser();
-          }
-          return result; // Important! A failure can indicate that the parser should block!
-        }
-      }
+      return mPrototype->AddOverlayReference(url);
     }
 
-    return NS_OK;
+    targetStart = tmp;
+    if (!FindInReadable(NS_LITERAL_STRING("xml-stylesheet"), targetStart,
+                        targetEnd)) {
+        return NS_OK;
+    }
+
+    // It's a stylesheet PI...
+    nsAutoString type;
+    nsParserUtils::GetQuotedAttributeValue(data, nsGkAtoms::type, type);
+
+    nsAutoString href, title, media;
+    PRBool isAlternate = PR_FALSE;
+    nsXMLContentSink::ParsePIData(data, href, title, media, isAlternate);
+
+    // If there was no href, we can't do anything with this PI
+    if (href.IsEmpty()) {
+        return NS_OK;
+    }
+
+    // XXX need a node here
+    rv = ProcessStyleLink(nsnull , href, isAlternate, title, type, media);
+    if (rv == NS_ERROR_HTMLPARSER_BLOCK && mParser) {
+        mParser->BlockParser();
+    }
+
+    return rv;
 }
 
 
diff --git a/parser/expat/lib/moz_extensions.c b/parser/expat/lib/moz_extensions.c
index cce97d86090e..3c43e47c9292 100644
--- a/parser/expat/lib/moz_extensions.c
+++ b/parser/expat/lib/moz_extensions.c
@@ -39,13 +39,15 @@
 
 #ifdef IS_LITTLE_ENDIAN
 
-#define BYTE_TYPE(p) LITTLE2_BYTE_TYPE(&little2_encoding_ns, p)
+#define PREFIX(ident) little2_ ## ident
+#define BYTE_TYPE(p) LITTLE2_BYTE_TYPE(XmlGetUtf16InternalEncodingNS(), p)
 #define IS_NAME_CHAR_MINBPC(p) LITTLE2_IS_NAME_CHAR_MINBPC(0, p)
 #define IS_NMSTRT_CHAR_MINBPC(p) LITTLE2_IS_NMSTRT_CHAR_MINBPC(0, p)
 
 #else
 
-#define BYTE_TYPE(p) BIG2_BYTE_TYPE(&big2_encoding_ns, p)
+#define PREFIX(ident) big2_ ## ident
+#define BYTE_TYPE(p) BIG2_BYTE_TYPE(XmlGetUtf16InternalEncodingNS(), p)
 #define IS_NAME_CHAR_MINBPC(p) BIG2_IS_NAME_CHAR_MINBPC(0, p)
 #define IS_NMSTRT_CHAR_MINBPC(p) BIG2_IS_NMSTRT_CHAR_MINBPC(0, p)
 
@@ -151,8 +153,43 @@ int MOZ_XMLIsNCNameChar(const char* ptr)
   }
 }
 
+int MOZ_XMLTranslateEntity(const char* ptr, const char* end, const char** next,
+                           XML_Char* result)
+{
+  const ENCODING* enc = XmlGetUtf16InternalEncodingNS();
+  int tok = PREFIX(scanRef)(enc, ptr, end, next);
+  if (tok <= XML_TOK_INVALID) {
+    return 0;
+  }
+
+  if (tok == XML_TOK_CHAR_REF) {
+    int n = XmlCharRefNumber(enc, ptr);
+
+    // We could get away with just < 0, but better safe than sorry.
+    if (n <= 0) {
+      return 0;
+    }
+
+    return XmlUtf16Encode(n, (unsigned short*)result);
+  }
+
+  if (tok == XML_TOK_ENTITY_REF) {
+    // *next points to after the semicolon, so the entity ends at
+    // *next - enc->minBytesPerChar.
+    XML_Char ch =
+      (XML_Char)XmlPredefinedEntityName(enc, ptr, *next - enc->minBytesPerChar);
+    if (!ch) {
+      return 0;
+    }
+
+    *result = ch;
+    return 1;
+  }
+
+  return 0;
+}
+
+#undef PREFIX
 #undef BYTE_TYPE
 #undef IS_NAME_CHAR_MINBPC
 #undef IS_NMSTRT_CHAR_MINBPC
-#undef CHECK_NAME_CASES
-#undef CHECK_NMSTRT_CASES
diff --git a/parser/htmlparser/public/nsIParserService.h b/parser/htmlparser/public/nsIParserService.h
index 40c7ba6ed3e9..04f5a97773a4 100644
--- a/parser/htmlparser/public/nsIParserService.h
+++ b/parser/htmlparser/public/nsIParserService.h
@@ -160,6 +160,25 @@ class nsIParserService : public nsISupports {
                               const PRUnichar** aColon) = 0;
   virtual PRBool IsXMLLetter(PRUnichar aChar) = 0;
   virtual PRBool IsXMLNCNameChar(PRUnichar aChar) = 0;
+
+  /**
+   * Decodes an entity into a UTF-16 character. If a ; is found between aStart
+   * and aEnd it will try to decode the entity and set aNext to point to the
+   * character after the ;. The resulting UTF-16 character will be written in
+   * aResult, so if the entity is a valid numeric entity there needs to be
+   * space for at least two PRUnichars.
+   *
+   * @param aStart pointer to the character after the ampersand. 
+   * @param aEnd pointer to the position after the last character of the
+   *             string.
+   * @param aNext [out] will be set to the character after the ; or null if
+   *                    the decoding was unsuccessful.
+   * @param aResult the buffer to write the resulting UTF-16 character in.
+   * @return the number of PRUnichars written to aResult.
+   */
+  virtual PRUint32 DecodeEntity(const PRUnichar* aStart, const PRUnichar* aEnd,
+                                const PRUnichar** aNext,
+                                PRUnichar* aResult) = 0;
 };
 
 NS_DEFINE_STATIC_IID_ACCESSOR(nsIParserService, NS_IPARSERSERVICE_IID)
diff --git a/parser/htmlparser/src/nsParserService.h b/parser/htmlparser/src/nsParserService.h
index 3e37f46e22e7..e0461514a174 100644
--- a/parser/htmlparser/src/nsParserService.h
+++ b/parser/htmlparser/src/nsParserService.h
@@ -44,6 +44,8 @@
 
 extern "C" int MOZ_XMLIsLetter(const char* ptr);
 extern "C" int MOZ_XMLIsNCNameChar(const char* ptr);
+extern "C" PRBool MOZ_XMLTranslateEntity(const char* ptr, const char* end,
+                                         const char** next, PRUnichar* result);
 
 class nsParserService : public nsIParserService {
 public:
@@ -90,6 +92,15 @@ public:
   {
     return MOZ_XMLIsNCNameChar(NS_REINTERPRET_CAST(const char*, &aChar));
   }
+  PRUint32 DecodeEntity(const PRUnichar* aStart, const PRUnichar* aEnd,
+                        const PRUnichar** aNext, PRUnichar* aResult)
+  {
+    *aNext = nsnull;
+    return MOZ_XMLTranslateEntity(NS_REINTERPRET_CAST(const char*, aStart),
+                                  NS_REINTERPRET_CAST(const char*, aEnd),
+                                  NS_REINTERPRET_CAST(const char**, aNext),
+                                  aResult);
+  }
 
 protected:
   nsObserverEntry* GetEntry(const nsAString& aTopic);