diff -r 000000000000 -r 6474c204b198 dom/xslt/xpath/txFilterExpr.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/xslt/xpath/txFilterExpr.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,94 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "txExpr.h"
+#include "txNodeSet.h"
+#include "txIXPathContext.h"
+
+//-- Implementation of FilterExpr --/
+
+  //-----------------------------/
+ //- Virtual methods from Expr -/
+//-----------------------------/
+
+/**
+ * Evaluates this Expr based on the given context node and processor state
+ * @param context the context node for evaluation of this Expr
+ * @param ps the ProcessorState containing the stack information needed
+ * for evaluation
+ * @return the result of the evaluation
+ * @see Expr
+**/
+nsresult
+FilterExpr::evaluate(txIEvalContext* aContext, txAExprResult** aResult)
+{
+    *aResult = nullptr;
+
+    nsRefPtr<txAExprResult> exprRes;
+    nsresult rv = expr->evaluate(aContext, getter_AddRefs(exprRes));
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    NS_ENSURE_TRUE(exprRes->getResultType() == txAExprResult::NODESET,
+                   NS_ERROR_XSLT_NODESET_EXPECTED);
+
+    nsRefPtr<txNodeSet> nodes =
+        static_cast<txNodeSet*>(static_cast<txAExprResult*>(exprRes));
+    // null out exprRes so that we can test for shared-ness
+    exprRes = nullptr;
+
+    nsRefPtr<txNodeSet> nonShared;
+    rv = aContext->recycler()->getNonSharedNodeSet(nodes,
+                                                   getter_AddRefs(nonShared));
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    rv = evaluatePredicates(nonShared, aContext);
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    *aResult = nonShared;
+    NS_ADDREF(*aResult);
+
+    return NS_OK;
+} //-- evaluate
+
+TX_IMPL_EXPR_STUBS_BASE(FilterExpr, NODESET_RESULT)
+
+Expr*
+FilterExpr::getSubExprAt(uint32_t aPos)
+{
+    if (aPos == 0) {
+      return expr;
+    }
+    return PredicateList::getSubExprAt(aPos - 1);
+}
+
+void
+FilterExpr::setSubExprAt(uint32_t aPos, Expr* aExpr)
+{
+    if (aPos == 0) {
+      expr.forget();
+      expr = aExpr;
+    }
+    else {
+      PredicateList::setSubExprAt(aPos - 1, aExpr);
+    }
+}
+
+bool
+FilterExpr::isSensitiveTo(ContextSensitivity aContext)
+{
+    return expr->isSensitiveTo(aContext) ||
+           PredicateList::isSensitiveTo(aContext);
+}
+
+#ifdef TX_TO_STRING
+void
+FilterExpr::toString(nsAString& str)
+{
+    if ( expr ) expr->toString(str);
+    else str.AppendLiteral("null");
+    PredicateList::toString(str);
+}
+#endif
+