diff -r 000000000000 -r 6474c204b198 js/src/builtin/TypedObjectConstants.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/builtin/TypedObjectConstants.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,112 @@
+/* -*- 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/. */
+
+// Specialized .h file to be used by both JS and C++ code.
+
+#ifndef builtin_TypedObjectConstants_h
+#define builtin_TypedObjectConstants_h
+
+///////////////////////////////////////////////////////////////////////////
+// Slots for typed prototypes
+
+#define JS_TYPROTO_SLOT_DESCR            0
+#define JS_TYPROTO_SLOTS                 1
+
+///////////////////////////////////////////////////////////////////////////
+// Slots for type objects
+//
+// Some slots apply to all type objects and some are specific to
+// particular kinds of type objects. For simplicity we use the same
+// number of slots no matter what kind of type descriptor we are
+// working with, even though this is mildly wasteful.
+
+// Slots on all type objects
+#define JS_DESCR_SLOT_KIND               0  // Atomized string representation
+#define JS_DESCR_SLOT_STRING_REPR        1  // Atomized string representation
+#define JS_DESCR_SLOT_ALIGNMENT          2  // Alignment in bytes
+#define JS_DESCR_SLOT_SIZE               3  // Size in bytes, if sized, else 0
+#define JS_DESCR_SLOT_OPAQUE             4  // Atomized string representation
+#define JS_DESCR_SLOT_TYPROTO            5  // Prototype for instances, if any
+
+// Slots on scalars, references, and x4s
+#define JS_DESCR_SLOT_TYPE               6  // Type code
+
+// Slots on all array descriptors
+#define JS_DESCR_SLOT_ARRAY_ELEM_TYPE    6
+
+// Slots on sized array descriptors
+#define JS_DESCR_SLOT_SIZED_ARRAY_LENGTH 7
+
+// Slots on struct type objects
+#define JS_DESCR_SLOT_STRUCT_FIELD_NAMES 6
+#define JS_DESCR_SLOT_STRUCT_FIELD_TYPES 7
+#define JS_DESCR_SLOT_STRUCT_FIELD_OFFSETS 8
+
+// Maximum number of slots for any descriptor
+#define JS_DESCR_SLOTS                   9
+
+// These constants are for use exclusively in JS code. In C++ code,
+// prefer TypeRepresentation::Scalar etc, which allows you to
+// write a switch which will receive a warning if you omit a case.
+#define JS_TYPEREPR_UNSIZED_ARRAY_KIND  0
+#define JS_TYPEREPR_MAX_UNSIZED_KIND    0    // Unsized kinds go above here
+#define JS_TYPEREPR_SCALAR_KIND         1
+#define JS_TYPEREPR_REFERENCE_KIND      2
+#define JS_TYPEREPR_STRUCT_KIND         3
+#define JS_TYPEREPR_SIZED_ARRAY_KIND    4
+#define JS_TYPEREPR_X4_KIND             5
+
+// These constants are for use exclusively in JS code. In C++ code,
+// prefer ScalarTypeRepresentation::TYPE_INT8 etc, which allows
+// you to write a switch which will receive a warning if you omit a
+// case.
+#define JS_SCALARTYPEREPR_INT8          0
+#define JS_SCALARTYPEREPR_UINT8         1
+#define JS_SCALARTYPEREPR_INT16         2
+#define JS_SCALARTYPEREPR_UINT16        3
+#define JS_SCALARTYPEREPR_INT32         4
+#define JS_SCALARTYPEREPR_UINT32        5
+#define JS_SCALARTYPEREPR_FLOAT32       6
+#define JS_SCALARTYPEREPR_FLOAT64       7
+#define JS_SCALARTYPEREPR_UINT8_CLAMPED 8
+
+// These constants are for use exclusively in JS code. In C++ code,
+// prefer ReferenceTypeRepresentation::TYPE_ANY etc, which allows
+// you to write a switch which will receive a warning if you omit a
+// case.
+#define JS_REFERENCETYPEREPR_ANY        0
+#define JS_REFERENCETYPEREPR_OBJECT     1
+#define JS_REFERENCETYPEREPR_STRING     2
+
+// These constants are for use exclusively in JS code.  In C++ code,
+// prefer X4TypeRepresentation::TYPE_INT32 etc, since that allows
+// you to write a switch which will receive a warning if you omit a
+// case.
+#define JS_X4TYPEREPR_INT32         0
+#define JS_X4TYPEREPR_FLOAT32       1
+
+///////////////////////////////////////////////////////////////////////////
+// Slots for typed objects
+
+#define JS_TYPEDOBJ_SLOT_BYTEOFFSET       0
+#define JS_TYPEDOBJ_SLOT_BYTELENGTH       1
+#define JS_TYPEDOBJ_SLOT_OWNER            2
+#define JS_TYPEDOBJ_SLOT_NEXT_VIEW        3
+
+#define JS_DATAVIEW_SLOTS              4 // Number of slots for data views
+
+#define JS_TYPEDOBJ_SLOT_LENGTH           4 // Length of array (see (*) below)
+#define JS_TYPEDOBJ_SLOT_TYPE_DESCR       5 // For typed objects, type descr
+
+#define JS_TYPEDOBJ_SLOT_DATA             7 // private slot, based on alloc kind
+#define JS_TYPEDOBJ_SLOTS                 6 // Number of slots for typed objs
+
+// (*) The JS_TYPEDOBJ_SLOT_LENGTH slot stores the length for typed objects of
+// sized and unsized array type. The slot contains 0 for non-arrays.
+// The slot also contains 0 for *unattached* typed objects, no matter what
+// type they have.
+
+#endif