diff -r 000000000000 -r 6474c204b198 js/src/vm/ErrorObject.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/vm/ErrorObject.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,101 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * 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/. */
+
+#ifndef vm_ErrorObject_h_
+#define vm_ErrorObject_h_
+
+#include "jsobj.h"
+
+#include "vm/Shape.h"
+
+struct JSExnPrivate;
+
+/*
+ * Initialize the exception constructor/prototype hierarchy.
+ */
+extern JSObject *
+js_InitExceptionClasses(JSContext *cx, JS::HandleObject obj);
+
+namespace js {
+
+class ErrorObject : public JSObject
+{
+    static ErrorObject *
+    createProto(JSContext *cx, JS::Handle<GlobalObject*> global, JSExnType type,
+                JS::HandleObject proto);
+
+    /* For access to createProto. */
+    friend JSObject *
+    ::js_InitExceptionClasses(JSContext *cx, JS::HandleObject global);
+
+    /* For access to assignInitialShape. */
+    friend bool
+    EmptyShape::ensureInitialCustomShape<ErrorObject>(ExclusiveContext *cx,
+                                                      Handle<ErrorObject*> obj);
+
+    /*
+     * Assign the initial error shape to the empty object.  (This shape does
+     * *not* include .message, which must be added separately if needed; see
+     * ErrorObject::init.)
+     */
+    static Shape *
+    assignInitialShape(ExclusiveContext *cx, Handle<ErrorObject*> obj);
+
+    static bool
+    init(JSContext *cx, Handle<ErrorObject*> obj, JSExnType type,
+         ScopedJSFreePtr<JSErrorReport> *errorReport, HandleString fileName, HandleString stack,
+         uint32_t lineNumber, uint32_t columnNumber, HandleString message);
+
+  protected:
+    static const uint32_t EXNTYPE_SLOT      = 0;
+    static const uint32_t ERROR_REPORT_SLOT = EXNTYPE_SLOT + 1;
+    static const uint32_t FILENAME_SLOT     = ERROR_REPORT_SLOT + 1;
+    static const uint32_t LINENUMBER_SLOT   = FILENAME_SLOT + 1;
+    static const uint32_t COLUMNNUMBER_SLOT = LINENUMBER_SLOT + 1;
+    static const uint32_t STACK_SLOT        = COLUMNNUMBER_SLOT + 1;
+    static const uint32_t MESSAGE_SLOT      = STACK_SLOT + 1;
+
+    static const uint32_t RESERVED_SLOTS = MESSAGE_SLOT + 1;
+
+  public:
+    static const Class class_;
+
+    // Create an error of the given type corresponding to the provided location
+    // info.  If |message| is non-null, then the error will have a .message
+    // property with that value; otherwise the error will have no .message
+    // property.
+    static ErrorObject *
+    create(JSContext *cx, JSExnType type, HandleString stack, HandleString fileName,
+           uint32_t lineNumber, uint32_t columnNumber, ScopedJSFreePtr<JSErrorReport> *report,
+           HandleString message);
+
+    JSExnType type() const {
+        return JSExnType(getReservedSlot(EXNTYPE_SLOT).toInt32());
+    }
+
+    JSErrorReport * getErrorReport() const {
+        const Value &slot = getReservedSlot(ERROR_REPORT_SLOT);
+        if (slot.isUndefined())
+            return nullptr;
+        return static_cast<JSErrorReport*>(slot.toPrivate());
+    }
+
+    JSErrorReport * getOrCreateErrorReport(JSContext *cx);
+
+    inline JSString * fileName(JSContext *cx) const;
+    inline uint32_t lineNumber() const;
+    inline uint32_t columnNumber() const;
+    inline JSString * stack(JSContext *cx) const;
+
+    JSString * getMessage() const {
+        const HeapSlot &slot = getReservedSlotRef(MESSAGE_SLOT);
+        return slot.isString() ? slot.toString() : nullptr;
+    }
+};
+
+} // namespace js
+
+#endif // vm_ErrorObject_h_