diff -r 000000000000 -r 6474c204b198 layout/style/CSS.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/layout/style/CSS.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,98 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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/. */
+
+/* DOM object holding utility CSS functions */
+
+#include "CSS.h"
+
+#include "mozilla/dom/BindingDeclarations.h"
+#include "nsCSSParser.h"
+#include "nsGlobalWindow.h"
+#include "nsIDocument.h"
+#include "nsIURI.h"
+#include "nsStyleUtil.h"
+
+namespace mozilla {
+namespace dom {
+
+struct SupportsParsingInfo
+{
+  nsIURI* mDocURI;
+  nsIURI* mBaseURI;
+  nsIPrincipal* mPrincipal;
+};
+
+static nsresult
+GetParsingInfo(nsISupports* aGlobal,
+               SupportsParsingInfo& aInfo)
+{
+  if (!aGlobal) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsGlobalWindow* win = nsGlobalWindow::FromSupports(aGlobal);
+  nsCOMPtr<nsIDocument> doc = win->GetDoc();
+  if (!doc) {
+    return NS_ERROR_FAILURE;
+  }
+
+  aInfo.mDocURI = nsCOMPtr<nsIURI>(doc->GetDocumentURI());
+  aInfo.mBaseURI = nsCOMPtr<nsIURI>(doc->GetBaseURI());
+  aInfo.mPrincipal = win->GetPrincipal();
+  return NS_OK;
+}
+
+/* static */ bool
+CSS::Supports(const GlobalObject& aGlobal,
+              const nsAString& aProperty,
+              const nsAString& aValue,
+              ErrorResult& aRv)
+{
+  nsCSSParser parser;
+  SupportsParsingInfo info;
+
+  nsresult rv = GetParsingInfo(aGlobal.GetAsSupports(), info);
+  if (NS_FAILED(rv)) {
+    aRv.Throw(rv);
+    return false;
+  }
+
+  return parser.EvaluateSupportsDeclaration(aProperty, aValue, info.mDocURI,
+                                            info.mBaseURI, info.mPrincipal);
+}
+
+/* static */ bool
+CSS::Supports(const GlobalObject& aGlobal,
+              const nsAString& aCondition,
+              ErrorResult& aRv)
+{
+  nsCSSParser parser;
+  SupportsParsingInfo info;
+
+  nsresult rv = GetParsingInfo(aGlobal.GetAsSupports(), info);
+  if (NS_FAILED(rv)) {
+    aRv.Throw(rv);
+    return false;
+  }
+
+  return parser.EvaluateSupportsCondition(aCondition, info.mDocURI,
+                                          info.mBaseURI, info.mPrincipal);
+}
+
+/* static */ void
+CSS::Escape(const GlobalObject& aGlobal,
+            const nsAString& aIdent,
+            nsAString& aReturn,
+            ErrorResult& aRv)
+{
+  bool success = nsStyleUtil::AppendEscapedCSSIdent(aIdent, aReturn);
+
+  if (!success) {
+    aRv.Throw(NS_ERROR_DOM_INVALID_CHARACTER_ERR);
+  }
+}
+
+} // dom
+} // mozilla