diff --git a/dom/xbl/nsXBLDocumentInfo.cpp b/dom/xbl/nsXBLDocumentInfo.cpp
index f93791c5707..eae376863b8 100644
--- a/dom/xbl/nsXBLDocumentInfo.cpp
+++ b/dom/xbl/nsXBLDocumentInfo.cpp
@@ -223,20 +223,22 @@ nsXBLDocGlobalObject::GetPrincipal()
 
 /* Implementation file */
 
-static PLDHashOperator
-TraverseProtos(const nsACString &aKey, nsXBLPrototypeBinding *aProto, void* aClosure)
+static bool
+TraverseProtos(nsHashKey *aKey, void *aData, void* aClosure)
 {
-  nsCycleCollectionTraversalCallback *cb =
+  nsCycleCollectionTraversalCallback *cb = 
     static_cast<nsCycleCollectionTraversalCallback*>(aClosure);
-  aProto->Traverse(*cb);
-  return PL_DHASH_NEXT;
+  nsXBLPrototypeBinding *proto = static_cast<nsXBLPrototypeBinding*>(aData);
+  proto->Traverse(*cb);
+  return kHashEnumerateNext;
 }
 
-static PLDHashOperator
-UnlinkProtoJSObjects(const nsACString &aKey, nsXBLPrototypeBinding *aProto, void* aClosure)
+static bool
+UnlinkProtoJSObjects(nsHashKey *aKey, void *aData, void* aClosure)
 {
-  aProto->UnlinkJSObjects();
-  return PL_DHASH_NEXT;
+  nsXBLPrototypeBinding *proto = static_cast<nsXBLPrototypeBinding*>(aData);
+  proto->UnlinkJSObjects();
+  return kHashEnumerateNext;
 }
 
 struct ProtoTracer
@@ -245,19 +247,20 @@ struct ProtoTracer
   void *mClosure;
 };
 
-static PLDHashOperator
-TraceProtos(const nsACString &aKey, nsXBLPrototypeBinding *aProto, void* aClosure)
+static bool
+TraceProtos(nsHashKey *aKey, void *aData, void* aClosure)
 {
   ProtoTracer* closure = static_cast<ProtoTracer*>(aClosure);
-  aProto->Trace(closure->mCallbacks, closure->mClosure);
-  return PL_DHASH_NEXT;
+  nsXBLPrototypeBinding *proto = static_cast<nsXBLPrototypeBinding*>(aData);
+  proto->Trace(closure->mCallbacks, closure->mClosure);
+  return kHashEnumerateNext;
 }
 
 NS_IMPL_CYCLE_COLLECTION_CLASS(nsXBLDocumentInfo)
 
 NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(nsXBLDocumentInfo)
   if (tmp->mBindingTable) {
-    tmp->mBindingTable->EnumerateRead(UnlinkProtoJSObjects, nullptr);
+    tmp->mBindingTable->Enumerate(UnlinkProtoJSObjects, nullptr);
   }
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mDocument)
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mGlobalObject)
@@ -270,7 +273,7 @@ NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(nsXBLDocumentInfo)
   }
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mDocument)
   if (tmp->mBindingTable) {
-    tmp->mBindingTable->EnumerateRead(TraverseProtos, &cb);
+    tmp->mBindingTable->Enumerate(TraverseProtos, &cb);
   }
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mGlobalObject)
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE_SCRIPT_OBJECTS
@@ -278,7 +281,7 @@ NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
 NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN(nsXBLDocumentInfo)
   if (tmp->mBindingTable) {
     ProtoTracer closure = { aCallbacks, aClosure };
-    tmp->mBindingTable->EnumerateRead(TraceProtos, &closure);
+    tmp->mBindingTable->Enumerate(TraceProtos, &closure);
   }
 NS_IMPL_CYCLE_COLLECTION_TRACE_END
 
@@ -288,11 +291,12 @@ UnmarkXBLJSObject(void* aP, const char* aName, void* aClosure)
   JS::ExposeObjectToActiveJS(static_cast<JSObject*>(aP));
 }
 
-static PLDHashOperator
-UnmarkProtos(const nsACString &aKey, nsXBLPrototypeBinding *aProto, void* aClosure)
+static bool
+UnmarkProtos(nsHashKey* aKey, void* aData, void* aClosure)
 {
-  aProto->Trace(TraceCallbackFunc(UnmarkXBLJSObject), nullptr);
-  return PL_DHASH_NEXT;
+  nsXBLPrototypeBinding* proto = static_cast<nsXBLPrototypeBinding*>(aData);
+  proto->Trace(TraceCallbackFunc(UnmarkXBLJSObject), nullptr);
+  return kHashEnumerateNext;
 }
 
 void
@@ -303,7 +307,7 @@ nsXBLDocumentInfo::MarkInCCGeneration(uint32_t aGeneration)
   }
   // Unmark any JS we hold
   if (mBindingTable) {
-    mBindingTable->EnumerateRead(UnmarkProtos, nullptr);
+    mBindingTable->Enumerate(UnmarkProtos, nullptr);
   }
   if (mGlobalObject) {
     mGlobalObject->UnmarkCompilationGlobal();
@@ -322,6 +326,7 @@ nsXBLDocumentInfo::nsXBLDocumentInfo(nsIDocument* aDocument)
   : mDocument(aDocument),
     mScriptAccess(true),
     mIsChrome(false),
+    mBindingTable(nullptr),
     mFirstBinding(nullptr)
 {
   nsIURI* uri = aDocument->GetDocumentURI();
@@ -362,7 +367,11 @@ nsXBLDocumentInfo::~nsXBLDocumentInfo()
   if (mGlobalObject) {
     mGlobalObject->ClearGlobalObjectOwner(); // just in case
   }
-  mozilla::DropJSObjects(this);
+  if (mBindingTable) {
+    delete mBindingTable;
+    mBindingTable = nullptr;
+    mozilla::DropJSObjects(this);
+  }
 }
 
 nsXBLPrototypeBinding*
@@ -376,19 +385,32 @@ nsXBLDocumentInfo::GetPrototypeBinding(const nsACString& aRef)
     return mFirstBinding;
   }
 
-  return mBindingTable->Get(aRef);
+  const nsPromiseFlatCString& flat = PromiseFlatCString(aRef);
+  nsCStringKey key(flat.get());
+  return static_cast<nsXBLPrototypeBinding*>(mBindingTable->Get(&key));
+}
+
+static bool
+DeletePrototypeBinding(nsHashKey* aKey, void* aData, void* aClosure)
+{
+  nsXBLPrototypeBinding* binding = static_cast<nsXBLPrototypeBinding*>(aData);
+  delete binding;
+  return true;
 }
 
 nsresult
 nsXBLDocumentInfo::SetPrototypeBinding(const nsACString& aRef, nsXBLPrototypeBinding* aBinding)
 {
   if (!mBindingTable) {
-    mBindingTable = new nsClassHashtable<nsCStringHashKey, nsXBLPrototypeBinding>();
+    mBindingTable = new nsObjectHashtable(nullptr, nullptr, DeletePrototypeBinding, nullptr);
+
     mozilla::HoldJSObjects(this);
   }
 
-  NS_ENSURE_STATE(!mBindingTable->Get(aRef));
-  mBindingTable->Put(aRef, aBinding);
+  const nsPromiseFlatCString& flat = PromiseFlatCString(aRef);
+  nsCStringKey key(flat.get());
+  NS_ENSURE_STATE(!mBindingTable->Get(&key));
+  mBindingTable->Put(&key, aBinding);
 
   return NS_OK;
 }
@@ -397,18 +419,22 @@ void
 nsXBLDocumentInfo::RemovePrototypeBinding(const nsACString& aRef)
 {
   if (mBindingTable) {
-    mBindingTable->Remove(aRef);
+    // Use a flat string to avoid making a copy.
+    const nsPromiseFlatCString& flat = PromiseFlatCString(aRef);
+    nsCStringKey key(flat);
+    mBindingTable->Remove(&key);
   }
 }
 
 // Callback to enumerate over the bindings from this document and write them
 // out to the cache.
-static PLDHashOperator
-WriteBinding(const nsACString &aKey, nsXBLPrototypeBinding *aProto, void* aClosure)
+bool
+WriteBinding(nsHashKey *aKey, void *aData, void* aClosure)
 {
-  aProto->Write((nsIObjectOutputStream*)aClosure);
+  nsXBLPrototypeBinding* binding = static_cast<nsXBLPrototypeBinding *>(aData);
+  binding->Write((nsIObjectOutputStream*)aClosure);
 
-  return PL_DHASH_NEXT;
+  return kHashEnumerateNext;
 }
 
 // static
@@ -504,9 +530,8 @@ nsXBLDocumentInfo::WritePrototypeBindings()
   rv = stream->Write32(XBLBinding_Serialize_Version);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  if (mBindingTable) {
-    mBindingTable->EnumerateRead(WriteBinding, stream);
-  }
+  if (mBindingTable)
+    mBindingTable->Enumerate(WriteBinding, stream);
 
   // write a end marker at the end
   rv = stream->Write8(XBLBinding_Serialize_NoMoreBindings);
@@ -529,19 +554,18 @@ nsXBLDocumentInfo::SetFirstPrototypeBinding(nsXBLPrototypeBinding* aBinding)
   mFirstBinding = aBinding;
 }
 
-static PLDHashOperator
-FlushScopedSkinSheets(const nsACString &aKey, nsXBLPrototypeBinding *aProto, void* aClosure)
+bool FlushScopedSkinSheets(nsHashKey* aKey, void* aData, void* aClosure)
 {
-  aProto->FlushSkinSheets();
-  return PL_DHASH_NEXT;
+  nsXBLPrototypeBinding* proto = (nsXBLPrototypeBinding*)aData;
+  proto->FlushSkinSheets();
+  return true;
 }
 
 void
 nsXBLDocumentInfo::FlushSkinStylesheets()
 {
-  if (mBindingTable) {
-    mBindingTable->EnumerateRead(FlushScopedSkinSheets, nullptr);
-  }
+  if (mBindingTable)
+    mBindingTable->Enumerate(FlushScopedSkinSheets);
 }
 
 JSObject*
diff --git a/dom/xbl/nsXBLDocumentInfo.h b/dom/xbl/nsXBLDocumentInfo.h
index adbb00035c2..412738a4118 100644
--- a/dom/xbl/nsXBLDocumentInfo.h
+++ b/dom/xbl/nsXBLDocumentInfo.h
@@ -13,6 +13,7 @@
 #include "nsCycleCollectionParticipant.h"
 
 class nsXBLPrototypeBinding;
+class nsObjectHashtable;
 class nsXBLDocGlobalObject;
 
 class nsXBLDocumentInfo : public nsSupportsWeakReference
@@ -40,7 +41,7 @@ public:
   nsresult WritePrototypeBindings();
 
   void SetFirstPrototypeBinding(nsXBLPrototypeBinding* aBinding);
-
+  
   void FlushSkinStylesheets();
 
   bool IsChrome() { return mIsChrome; }
@@ -59,8 +60,7 @@ private:
   bool mScriptAccess;
   bool mIsChrome;
   // the binding table owns each nsXBLPrototypeBinding
-  nsAutoPtr<nsClassHashtable<nsCStringHashKey, nsXBLPrototypeBinding>> mBindingTable;
-
+  nsObjectHashtable* mBindingTable;
   // non-owning pointer to the first binding in the table
   nsXBLPrototypeBinding* mFirstBinding;
 
diff --git a/dom/xbl/nsXBLPrototypeBinding.cpp b/dom/xbl/nsXBLPrototypeBinding.cpp
index fb0530bc1c2..9953a3de3d7 100644
--- a/dom/xbl/nsXBLPrototypeBinding.cpp
+++ b/dom/xbl/nsXBLPrototypeBinding.cpp
@@ -100,6 +100,7 @@ nsXBLPrototypeBinding::nsXBLPrototypeBinding()
   mKeyHandlersRegistered(false),
   mChromeOnlyContent(false),
   mResources(nullptr),
+  mAttributeTable(nullptr),
   mBaseNameSpaceID(kNameSpaceID_None)
 {
   MOZ_COUNT_CTOR(nsXBLPrototypeBinding);
@@ -180,6 +181,7 @@ nsXBLPrototypeBinding::Initialize()
 nsXBLPrototypeBinding::~nsXBLPrototypeBinding(void)
 {
   delete mResources;
+  delete mAttributeTable;
   delete mImplementation;
   MOZ_COUNT_DTOR(nsXBLPrototypeBinding);
 }
@@ -323,12 +325,14 @@ nsXBLPrototypeBinding::AttributeChanged(nsIAtom* aAttribute,
 {
   if (!mAttributeTable)
     return;
-
-  InnerAttributeTable *attributesNS = mAttributeTable->Get(aNameSpaceID);
+  nsPRUint32Key nskey(aNameSpaceID);
+  nsObjectHashtable *attributesNS = static_cast<nsObjectHashtable*>(mAttributeTable->Get(&nskey));
   if (!attributesNS)
     return;
 
-  nsXBLAttributeEntry* xblAttr = attributesNS->Get(aAttribute);
+  nsISupportsKey key(aAttribute);
+  nsXBLAttributeEntry* xblAttr = static_cast<nsXBLAttributeEntry*>
+                                            (attributesNS->Get(&key));
   if (!xblAttr)
     return;
 
@@ -496,12 +500,12 @@ struct nsXBLAttrChangeData
 };
 
 // XXXbz this duplicates lots of AttributeChanged
-static PLDHashOperator
-SetAttrs(nsISupports* aKey, nsXBLAttributeEntry* aEntry, void* aClosure)
+bool SetAttrs(nsHashKey* aKey, void* aData, void* aClosure)
 {
+  nsXBLAttributeEntry* entry = static_cast<nsXBLAttributeEntry*>(aData);
   nsXBLAttrChangeData* changeData = static_cast<nsXBLAttrChangeData*>(aClosure);
 
-  nsIAtom* src = aEntry->GetSrcAttribute();
+  nsIAtom* src = entry->GetSrcAttribute();
   int32_t srcNs = changeData->mSrcNamespace;
   nsAutoString value;
   bool attrPresent = true;
@@ -525,7 +529,7 @@ SetAttrs(nsISupports* aKey, nsXBLAttributeEntry* aEntry, void* aClosure)
     nsIContent* content =
       changeData->mProto->GetImmediateChild(nsGkAtoms::content);
 
-    nsXBLAttributeEntry* curr = aEntry;
+    nsXBLAttributeEntry* curr = entry;
     while (curr) {
       nsIAtom* dst = curr->GetDstAttribute();
       int32_t dstNs = curr->GetDstNameSpace();
@@ -556,20 +560,21 @@ SetAttrs(nsISupports* aKey, nsXBLAttributeEntry* aEntry, void* aClosure)
     }
   }
 
-  return PL_DHASH_NEXT;
+  return true;
 }
 
-static PLDHashOperator
-SetAttrsNS(const uint32_t &aNamespace,
-           nsXBLPrototypeBinding::InnerAttributeTable* aXBLAttributes,
-           void* aClosure)
+bool SetAttrsNS(nsHashKey* aKey, void* aData, void* aClosure)
 {
-  if (aXBLAttributes && aClosure) {
-    nsXBLAttrChangeData* changeData = static_cast<nsXBLAttrChangeData*>(aClosure);
-    changeData->mSrcNamespace = aNamespace;
-    aXBLAttributes->EnumerateRead(SetAttrs, aClosure);
+  if (aData && aClosure) {
+    nsPRUint32Key * key = static_cast<nsPRUint32Key*>(aKey);
+    nsObjectHashtable* xblAttributes =
+      static_cast<nsObjectHashtable*>(aData);
+    nsXBLAttrChangeData * changeData = static_cast<nsXBLAttrChangeData *>
+                                                  (aClosure);
+    changeData->mSrcNamespace = key->GetValue();
+    xblAttributes->Enumerate(SetAttrs, (void*)changeData);
   }
-  return PL_DHASH_NEXT;
+  return true;
 }
 
 void
@@ -577,7 +582,7 @@ nsXBLPrototypeBinding::SetInitialAttributes(nsIContent* aBoundElement, nsIConten
 {
   if (mAttributeTable) {
     nsXBLAttrChangeData data(this, aBoundElement, aAnonymousContent);
-    mAttributeTable->EnumerateRead(SetAttrsNS, &data);
+    mAttributeTable->Enumerate(SetAttrsNS, (void*)&data);
   }
 }
 
@@ -611,11 +616,27 @@ nsXBLPrototypeBinding::GetStyleSheets()
   return nullptr;
 }
 
+static bool
+DeleteAttributeEntry(nsHashKey* aKey, void* aData, void* aClosure)
+{
+  delete static_cast<nsXBLAttributeEntry*>(aData);
+  return true;
+}
+
+static bool
+DeleteAttributeTable(nsHashKey* aKey, void* aData, void* aClosure)
+{
+  delete static_cast<nsObjectHashtable*>(aData);
+  return true;
+}
+
 void
 nsXBLPrototypeBinding::EnsureAttributeTable()
 {
   if (!mAttributeTable) {
-    mAttributeTable = new nsClassHashtable<nsUint32HashKey, InnerAttributeTable>(4);
+    mAttributeTable = new nsObjectHashtable(nullptr, nullptr,
+                                            DeleteAttributeTable,
+                                            nullptr, 4);
   }
 }
 
@@ -624,18 +645,24 @@ nsXBLPrototypeBinding::AddToAttributeTable(int32_t aSourceNamespaceID, nsIAtom*
                                            int32_t aDestNamespaceID, nsIAtom* aDestTag,
                                            nsIContent* aContent)
 {
-    InnerAttributeTable* attributesNS = mAttributeTable->Get(aSourceNamespaceID);
+    nsPRUint32Key nskey(aSourceNamespaceID);
+    nsObjectHashtable* attributesNS =
+      static_cast<nsObjectHashtable*>(mAttributeTable->Get(&nskey));
     if (!attributesNS) {
-      attributesNS = new InnerAttributeTable(4);
-      mAttributeTable->Put(aSourceNamespaceID, attributesNS);
+      attributesNS = new nsObjectHashtable(nullptr, nullptr,
+                                           DeleteAttributeEntry,
+                                           nullptr, 4);
+      mAttributeTable->Put(&nskey, attributesNS);
     }
 
     nsXBLAttributeEntry* xblAttr =
       new nsXBLAttributeEntry(aSourceTag, aDestTag, aDestNamespaceID, aContent);
 
-    nsXBLAttributeEntry* entry = attributesNS->Get(aSourceTag);
+    nsISupportsKey key(aSourceTag);
+    nsXBLAttributeEntry* entry = static_cast<nsXBLAttributeEntry*>
+                                            (attributesNS->Get(&key));
     if (!entry) {
-      attributesNS->Put(aSourceTag, xblAttr);
+      attributesNS->Put(&key, xblAttr);
     } else {
       while (entry->GetNext())
         entry = entry->GetNext();
@@ -1394,41 +1421,44 @@ struct WriteAttributeData
   { }
 };
 
-static PLDHashOperator
-WriteAttribute(nsISupports* aKey, nsXBLAttributeEntry* aEntry, void* aClosure)
+static
+bool
+WriteAttribute(nsHashKey *aKey, void *aData, void* aClosure)
 {
   WriteAttributeData* data = static_cast<WriteAttributeData *>(aClosure);
   nsIObjectOutputStream* stream = data->stream;
   const int32_t srcNamespace = data->srcNamespace;
 
+  nsXBLAttributeEntry* entry = static_cast<nsXBLAttributeEntry *>(aData);
   do {
-    if (aEntry->GetElement() == data->content) {
+    if (entry->GetElement() == data->content) {
       data->binding->WriteNamespace(stream, srcNamespace);
-      stream->WriteWStringZ(nsDependentAtomString(aEntry->GetSrcAttribute()).get());
-      data->binding->WriteNamespace(stream, aEntry->GetDstNameSpace());
-      stream->WriteWStringZ(nsDependentAtomString(aEntry->GetDstAttribute()).get());
+      stream->WriteWStringZ(nsDependentAtomString(entry->GetSrcAttribute()).get());
+      data->binding->WriteNamespace(stream, entry->GetDstNameSpace());
+      stream->WriteWStringZ(nsDependentAtomString(entry->GetDstAttribute()).get());
     }
 
-    aEntry = aEntry->GetNext();
-  } while (aEntry);
+    entry = entry->GetNext();
+  } while (entry);
 
-  return PL_DHASH_NEXT;
+  return kHashEnumerateNext;
 }
 
 // WriteAttributeNS is the callback to enumerate over the attribute
 // forwarding entries. Since these are stored in a hash of hashes,
 // we need to iterate over the inner hashes, calling WriteAttribute
 // to do the actual work.
-static PLDHashOperator
-WriteAttributeNS(const uint32_t &aNamespace,
-                 nsXBLPrototypeBinding::InnerAttributeTable* aXBLAttributes,
-                 void* aClosure)
+static
+bool
+WriteAttributeNS(nsHashKey *aKey, void *aData, void* aClosure)
 {
   WriteAttributeData* data = static_cast<WriteAttributeData *>(aClosure);
-  data->srcNamespace = aNamespace;
-  aXBLAttributes->EnumerateRead(WriteAttribute, data);
+  data->srcNamespace = static_cast<nsPRUint32Key *>(aKey)->GetValue();
 
-  return PL_DHASH_NEXT;
+  nsObjectHashtable* attributes = static_cast<nsObjectHashtable*>(aData);
+  attributes->Enumerate(WriteAttribute, data);
+
+  return kHashEnumerateNext;
 }
 
 nsresult
@@ -1512,7 +1542,7 @@ nsXBLPrototypeBinding::WriteContentNode(nsIObjectOutputStream* aStream,
   // Write out the attribute fowarding information
   if (mAttributeTable) {
     WriteAttributeData data(this, aStream, aNode);
-    mAttributeTable->EnumerateRead(WriteAttributeNS, &data);
+    mAttributeTable->Enumerate(WriteAttributeNS, &data);
   }
   rv = aStream->Write8(XBLBinding_Serialize_NoMoreAttributes);
   NS_ENSURE_SUCCESS(rv, rv);
diff --git a/dom/xbl/nsXBLPrototypeBinding.h b/dom/xbl/nsXBLPrototypeBinding.h
index 31eaa72e830..aa5be7e69f4 100644
--- a/dom/xbl/nsXBLPrototypeBinding.h
+++ b/dom/xbl/nsXBLPrototypeBinding.h
@@ -9,6 +9,7 @@
 #include "nsClassHashtable.h"
 #include "nsCOMArray.h"
 #include "nsCOMPtr.h"
+#include "nsHashtable.h"
 #include "nsICSSLoaderObserver.h"
 #include "nsInterfaceHashtable.h"
 #include "nsWeakReference.h"
@@ -21,9 +22,8 @@
 class nsIAtom;
 class nsIContent;
 class nsIDocument;
-class nsXBLAttributeEntry;
-class nsXBLBinding;
 class nsXBLProtoImplField;
+class nsXBLBinding;
 
 // *********************************************************************/
 // The XBLPrototypeBinding class
@@ -245,9 +245,6 @@ public:
                              nsIContent* aTemplChild);
 
   bool ChromeOnlyContent() { return mChromeOnlyContent; }
-
-  typedef nsClassHashtable<nsISupportsHashKey, nsXBLAttributeEntry> InnerAttributeTable;
-
 protected:
   // Ensure that mAttributeTable has been created.
   void EnsureAttributeTable();
@@ -281,10 +278,9 @@ protected:
 
   nsXBLDocumentInfo* mXBLDocInfoWeak; // A pointer back to our doc info.  Weak, since it owns us.
 
-  // A table for attribute containers. Namespace IDs are used as
-  // keys in the table. Containers are InnerAttributeTables.
-  // This table is used to efficiently handle attribute changes.
-  nsAutoPtr<nsClassHashtable<nsUint32HashKey, InnerAttributeTable>> mAttributeTable;
+  nsObjectHashtable* mAttributeTable; // A table for attribute containers. Namespace IDs are used as
+                                      // keys in the table. Containers are nsObjectHashtables.
+                                      // This table is used to efficiently handle attribute changes.
 
   class IIDHashKey : public PLDHashEntryHdr
   {