diff --git a/dom/src/base/Makefile.in b/dom/src/base/Makefile.in
index 41c4621d702d..0820083d8fa3 100644
--- a/dom/src/base/Makefile.in
+++ b/dom/src/base/Makefile.in
@@ -109,4 +109,6 @@ FORCE_STATIC_LIB = 1
 
 LOCAL_INCLUDES = -I$(srcdir)/../events
 
+DEFINES += -D_IMPL_NS_LAYOUT
+
 include $(topsrcdir)/config/rules.mk
diff --git a/dom/src/base/nsDOMClassInfo.cpp b/dom/src/base/nsDOMClassInfo.cpp
index 502aeefc8496..5bb4b58402a4 100644
--- a/dom/src/base/nsDOMClassInfo.cpp
+++ b/dom/src/base/nsDOMClassInfo.cpp
@@ -176,7 +176,9 @@
 #include "nsIDOMElement.h"
 #include "nsIDOMCSSStyleDeclaration.h"
 #include "nsIScriptGlobalObject.h"
-
+#include "nsStyleSet.h"
+#include "nsStyleContext.h"
+#include "nsAutoPtr.h"
 
 // includes needed for the prototype chain interfaces
 #include "nsIDOMNavigator.h"
@@ -4883,12 +4885,11 @@ nsElementSH::PostCreate(nsIXPConnectWrappedNative *wrapper, JSContext *cx,
   shell->GetPresContext(getter_AddRefs(pctx));
   NS_ENSURE_TRUE(pctx, NS_ERROR_UNEXPECTED);
 
-  // XXX this is a hack so that we don't take a performance hit by using
-  // the DOM computed style API.  We can get rid of this hack if we merge
-  // the jsdom library with layout.
+  nsRefPtr<nsStyleContext> sc = pctx->StyleSet()->ResolveStyleFor(content,
+                                                                  nsnull);
+  NS_ENSURE_TRUE(sc, NS_ERROR_FAILURE);
 
-  nsCOMPtr<nsIURI> bindingURL;
-  pctx->GetXBLBindingURL(content, getter_AddRefs(bindingURL));
+  nsIURI *bindingURL = sc->GetStyleDisplay()->mBinding;
   if (!bindingURL) {
     // No binding, nothing left to do here.
     return NS_OK;
diff --git a/layout/base/nsPresContext.cpp b/layout/base/nsPresContext.cpp
index 107843809329..6e7b129c885b 100644
--- a/layout/base/nsPresContext.cpp
+++ b/layout/base/nsPresContext.cpp
@@ -856,18 +856,6 @@ nsPresContext::SetImageAnimationMode(PRUint16 aMode)
   mImageAnimationMode = aMode;
 }
 
-nsresult
-nsPresContext::GetXBLBindingURL(nsIContent* aContent, nsIURI** aResult)
-{
-  nsRefPtr<nsStyleContext> sc;
-  sc = StyleSet()->ResolveStyleFor(aContent, nsnull);
-  NS_ENSURE_TRUE(sc, NS_ERROR_FAILURE);
-
-  *aResult = sc->GetStyleDisplay()->mBinding;
-  NS_IF_ADDREF(*aResult);
-  return NS_OK;
-}
-
 NS_IMETHODIMP
 nsPresContext::GetMetricsFor(const nsFont& aFont, nsIFontMetrics** aResult)
 {
diff --git a/layout/base/nsPresContext.h b/layout/base/nsPresContext.h
index a359678ecc72..f33b591aea82 100644
--- a/layout/base/nsPresContext.h
+++ b/layout/base/nsPresContext.h
@@ -78,8 +78,8 @@ class nsIRenderingContext;
 #endif
 
 #define NS_IPRESCONTEXT_IID   \
-{ 0x2820eeff, 0x7e66, 0x43df, \
-  {0xae, 0x19, 0xee, 0xf6, 0x09, 0xc1, 0xcf, 0xfe} }
+{ 0xa394329f, 0x3b10, 0x49ac, \
+  {0x8f, 0xf2, 0xeb, 0x0b, 0x66, 0x93, 0x82, 0x38} }
 
 enum nsWidgetType {
   eWidgetType_Button  	= 1,
@@ -175,13 +175,6 @@ public:
    */
   virtual void ClearStyleDataAndReflow() = 0;
 
-   /**
-    * Resolve a new style context for a content node and return the URL
-    * for its XBL binding, or null if it has no binding specified in CSS.
-    */
-  virtual nsresult GetXBLBindingURL(nsIContent* aContent,
-                                    nsIURI** aResult) = 0;
-
   void* AllocateFromShell(size_t aSize)
   {
     if (mShell)
diff --git a/layout/base/public/nsIPresContext.h b/layout/base/public/nsIPresContext.h
index a359678ecc72..f33b591aea82 100644
--- a/layout/base/public/nsIPresContext.h
+++ b/layout/base/public/nsIPresContext.h
@@ -78,8 +78,8 @@ class nsIRenderingContext;
 #endif
 
 #define NS_IPRESCONTEXT_IID   \
-{ 0x2820eeff, 0x7e66, 0x43df, \
-  {0xae, 0x19, 0xee, 0xf6, 0x09, 0xc1, 0xcf, 0xfe} }
+{ 0xa394329f, 0x3b10, 0x49ac, \
+  {0x8f, 0xf2, 0xeb, 0x0b, 0x66, 0x93, 0x82, 0x38} }
 
 enum nsWidgetType {
   eWidgetType_Button  	= 1,
@@ -175,13 +175,6 @@ public:
    */
   virtual void ClearStyleDataAndReflow() = 0;
 
-   /**
-    * Resolve a new style context for a content node and return the URL
-    * for its XBL binding, or null if it has no binding specified in CSS.
-    */
-  virtual nsresult GetXBLBindingURL(nsIContent* aContent,
-                                    nsIURI** aResult) = 0;
-
   void* AllocateFromShell(size_t aSize)
   {
     if (mShell)
diff --git a/layout/base/public/nsPresContext.h b/layout/base/public/nsPresContext.h
index a359678ecc72..f33b591aea82 100644
--- a/layout/base/public/nsPresContext.h
+++ b/layout/base/public/nsPresContext.h
@@ -78,8 +78,8 @@ class nsIRenderingContext;
 #endif
 
 #define NS_IPRESCONTEXT_IID   \
-{ 0x2820eeff, 0x7e66, 0x43df, \
-  {0xae, 0x19, 0xee, 0xf6, 0x09, 0xc1, 0xcf, 0xfe} }
+{ 0xa394329f, 0x3b10, 0x49ac, \
+  {0x8f, 0xf2, 0xeb, 0x0b, 0x66, 0x93, 0x82, 0x38} }
 
 enum nsWidgetType {
   eWidgetType_Button  	= 1,
@@ -175,13 +175,6 @@ public:
    */
   virtual void ClearStyleDataAndReflow() = 0;
 
-   /**
-    * Resolve a new style context for a content node and return the URL
-    * for its XBL binding, or null if it has no binding specified in CSS.
-    */
-  virtual nsresult GetXBLBindingURL(nsIContent* aContent,
-                                    nsIURI** aResult) = 0;
-
   void* AllocateFromShell(size_t aSize)
   {
     if (mShell)
diff --git a/layout/base/src/nsPresContext.cpp b/layout/base/src/nsPresContext.cpp
index 107843809329..6e7b129c885b 100644
--- a/layout/base/src/nsPresContext.cpp
+++ b/layout/base/src/nsPresContext.cpp
@@ -856,18 +856,6 @@ nsPresContext::SetImageAnimationMode(PRUint16 aMode)
   mImageAnimationMode = aMode;
 }
 
-nsresult
-nsPresContext::GetXBLBindingURL(nsIContent* aContent, nsIURI** aResult)
-{
-  nsRefPtr<nsStyleContext> sc;
-  sc = StyleSet()->ResolveStyleFor(aContent, nsnull);
-  NS_ENSURE_TRUE(sc, NS_ERROR_FAILURE);
-
-  *aResult = sc->GetStyleDisplay()->mBinding;
-  NS_IF_ADDREF(*aResult);
-  return NS_OK;
-}
-
 NS_IMETHODIMP
 nsPresContext::GetMetricsFor(const nsFont& aFont, nsIFontMetrics** aResult)
 {
diff --git a/layout/base/src/nsPresContext.h b/layout/base/src/nsPresContext.h
index c5ebd7e6bbc9..29b2b3a8c285 100644
--- a/layout/base/src/nsPresContext.h
+++ b/layout/base/src/nsPresContext.h
@@ -71,7 +71,6 @@ public:
   virtual void SetImageAnimationMode(PRUint16 aMode);
   virtual void ClearStyleDataAndReflow();
 
-  virtual nsresult GetXBLBindingURL(nsIContent* aContent, nsIURI** aResult);
   NS_IMETHOD GetMetricsFor(const nsFont& aFont, nsIFontMetrics** aResult);
   virtual const nsFont* GetDefaultFont(PRUint8 aFontID) const;