diff --git a/js/src/jstypedarray.cpp b/js/src/jstypedarray.cpp
index f4961b897982..e57e7e699377 100644
--- a/js/src/jstypedarray.cpp
+++ b/js/src/jstypedarray.cpp
@@ -70,7 +70,7 @@ using namespace js;
  * access.  It can be created explicitly and passed to a TypedArray, or
  * can be created implicitly by constructing a TypedArray with a size.
  */
-inline ArrayBuffer *
+ArrayBuffer *
 ArrayBuffer::fromJSObject(JSObject *obj)
 {
     JS_ASSERT(obj->getClass() == &ArrayBuffer::jsclass);
@@ -187,7 +187,7 @@ ArrayBuffer::~ArrayBuffer()
  * the subclasses.
  */
 
-inline TypedArray *
+TypedArray *
 TypedArray::fromJSObject(JSObject *obj)
 {
     return reinterpret_cast<TypedArray*>(obj->getPrivate());
@@ -1004,7 +1004,7 @@ TypedArrayTemplate<float>::copyIndexToValue(JSContext *cx, uint32 index, jsval *
 
 JSClass ArrayBuffer::jsclass = {
     "ArrayBuffer",
-    JSCLASS_HAS_PRIVATE,
+    JSCLASS_HAS_PRIVATE | JSCLASS_HAS_CACHED_PROTO(JSProto_ArrayBuffer),
     JS_PropertyStub, JS_PropertyStub, JS_PropertyStub, JS_PropertyStub,
     JS_EnumerateStub, JS_ResolveStub, JS_ConvertStub, ArrayBuffer::class_finalize,
     JSCLASS_NO_OPTIONAL_MEMBERS
@@ -1064,14 +1064,14 @@ template<> JSObjectOps _typedArray::fastObjectOps = {                          \
     NULL                                                                       \
 };                                                                             \
 template<> JSFunctionSpec _typedArray::jsfuncs[] = {                           \
-    JS_FN("slice", _typedArray::fun_slice, 2, JSFUN_GENERIC_NATIVE),           \
+    JS_FN("slice", _typedArray::fun_slice, 2, 0),                              \
     JS_FS_END                                                                  \
 }
 
 #define IMPL_TYPED_ARRAY_SLOW_CLASS(_typedArray)                               \
 {                                                                              \
     #_typedArray,                                                              \
-    JSCLASS_HAS_PRIVATE,                                                       \
+    JSCLASS_HAS_PRIVATE | JSCLASS_HAS_CACHED_PROTO(JSProto_##_typedArray),     \
     JS_PropertyStub, JS_PropertyStub, JS_PropertyStub, JS_PropertyStub,        \
     JS_EnumerateStub, JS_ResolveStub, JS_ConvertStub, JS_FinalizeStub,         \
     JSCLASS_NO_OPTIONAL_MEMBERS                                                \
@@ -1129,9 +1129,16 @@ JSClass TypedArray::slowClasses[TYPE_MAX] = {
     IMPL_TYPED_ARRAY_SLOW_CLASS(Float32Array)
 };
 
-JSObject *
+JS_FRIEND_API(JSObject *)
 js_InitTypedArrayClasses(JSContext *cx, JSObject *obj)
 {
+    /* Idempotency required: we initialize several things, possibly lazily. */
+    JSObject *stop;
+    if (!js_GetClassObject(cx, obj, JSProto_ArrayBuffer, &stop))
+        return NULL;
+    if (stop)
+        return stop;
+
     JSObject *proto;
 
     INIT_TYPED_ARRAY_CLASS(Int8Array,TYPE_INT8);
@@ -1148,8 +1155,7 @@ js_InitTypedArrayClasses(JSContext *cx, JSObject *obj)
     if (!proto)
         return NULL;
 
-    proto->setPrivate(0);
-
+    proto->setPrivate(NULL);
     return proto;
 }
 
diff --git a/js/src/jstypedarray.h b/js/src/jstypedarray.h
index cdb0b1271dd3..fd46e279230f 100644
--- a/js/src/jstypedarray.h
+++ b/js/src/jstypedarray.h
@@ -159,7 +159,7 @@ struct JS_FRIEND_API(TypedArray) {
 
 JS_BEGIN_EXTERN_C
 
-JSObject *
+JS_FRIEND_API(JSObject *)
 js_InitTypedArrayClasses(JSContext *cx, JSObject *obj);
 
 JS_FRIEND_API(JSBool)