--- a/content/base/public/nsDeprecatedOperationList.h
+++ b/content/base/public/nsDeprecatedOperationList.h
@@ -40,10 +40,11 @@ DEPRECATED_OPERATION(IsEqualNode)
 DEPRECATED_OPERATION(TextContent)
 DEPRECATED_OPERATION(EnablePrivilege)
 DEPRECATED_OPERATION(Position)
 DEPRECATED_OPERATION(TotalSize)
 DEPRECATED_OPERATION(InputEncoding)
 DEPRECATED_OPERATION(MozBeforePaint)
 DEPRECATED_OPERATION(MozBlobBuilder)
 DEPRECATED_OPERATION(DOMExceptionCode)
+DEPRECATED_OPERATION(NoExposedProps)
 DEPRECATED_OPERATION(MutationEvent)
 DEPRECATED_OPERATION(MozSlice)

--- a/js/xpconnect/tests/chrome/test_cows.xul
+++ b/js/xpconnect/tests/chrome/test_cows.xul
@@ -90,22 +90,20 @@ function COWTests() {
     //var cow = getCOW({ foo: "fooval", __exposedProps__: {}});
     //Math.sin(1);
     //is(cow.foo, undefined, "one test to rule them all");
     //return;
 
     const PROPS_TO_TEST = ['foo', 'bar', 'prototype'];
 
     var empty = {};
-    var nonempty = {foo: 42, bar: 33};
+    // Once we flip the default for __exposedProps__, this should behave
+    // the same as for function objects below.
     is(getCOW(empty).foo, undefined,
        "shouldn't throw when accessing exposed properties that doesn't exist");
-    PROPS_TO_TEST.forEach(function(name) {
-        isPropHidden(getCOW(nonempty), name, "object without exposedProps");
-    });
 
     // Test function objects without __exposedProps__
     var func = function(x) { return 42; };
     func.foo = "foo property";
     var funcCOW = getCOW(func);
     PROPS_TO_TEST.forEach(function(name) {
         isPropHidden(funcCOW, name, "function without exposedProps");
     });

--- a/js/xpconnect/wrappers/AccessCheck.cpp
+++ b/js/xpconnect/wrappers/AccessCheck.cpp
@@ -378,16 +378,26 @@ PermitIfUniversalXPConnect(JSContext *cx
         perm = ExposedPropertiesOnly::PermitPropertyAccess;
         return true; // Allow
     }
 
     // Deny
     return Deny(cx, id, act);
 }
 
+static bool
+IsInSandbox(JSContext *cx, JSObject *obj)
+{
+    JSAutoEnterCompartment ac;
+    if (!ac.enter(cx, obj))
+        return false;
+    JSObject *global = JS_GetGlobalForObject(cx, obj);
+    return !strcmp(js::GetObjectJSClass(global)->name, "Sandbox");
+}
+
 bool
 ExposedPropertiesOnly::check(JSContext *cx, JSObject *wrapper, jsid id, Wrapper::Action act,
                              Permission &perm)
 {
     JSObject *wrappedObject = Wrapper::wrappedObject(wrapper);
 
     if (act == Wrapper::CALL) {
         perm = PermitObjectAccess;
@@ -422,16 +432,36 @@ ExposedPropertiesOnly::check(JSContext *
     }
 
     // If no __exposedProps__ existed, deny access.
     if (!found) {
         // Everything below here needs to be done in the wrapper's compartment.
         if (!wrapperAC.enter(cx, wrapper))
             return false;
 
+        // Make a temporary exception for objects in a chrome sandbox to help
+        // out jetpack. See bug 784233.
+        if (!JS_ObjectIsFunction(cx, wrappedObject) &&
+            IsInSandbox(cx, wrappedObject))
+        {
+            // This little loop hole will go away soon! See bug 553102.
+            nsCOMPtr<nsPIDOMWindow> win =
+                do_QueryInterface(nsJSUtils::GetStaticScriptGlobal(cx, wrapper));
+            if (win) {
+                nsCOMPtr<nsIDocument> doc =
+                    do_QueryInterface(win->GetExtantDocument());
+                if (doc) {
+                    doc->WarnOnceAbout(nsIDocument::eNoExposedProps,
+                                       /* asError = */ true);
+                }
+            }
+
+            perm = PermitPropertyAccess;
+            return true;
+        }
         return PermitIfUniversalXPConnect(cx, id, act, perm); // Deny
     }
 
     if (id == JSID_VOID) {
         // This will force the caller to call us back for individual property accesses.
         perm = PermitPropertyAccess;
         return true;
     }