2 files changed, 21 insertions, 1 deletions
diff --git a/js/src/gc/Heap.h b/js/src/gc/Heap.h
index 697803380..7f2c5fb4f 100644
--- a/js/src/gc/Heap.h
+++ b/js/src/gc/Heap.h
@@ -29,6 +29,7 @@
 #include "js/HeapAPI.h"
 #include "js/RootingAPI.h"
 #include "js/TracingAPI.h"
+#include "js/TraceKind.h"
 
 struct JSRuntime;
 
@@ -273,6 +274,23 @@ struct Cell
 
     static MOZ_ALWAYS_INLINE bool needWriteBarrierPre(JS::Zone* zone);
 
+    template <class T>
+    inline bool is() const {
+        return getTraceKind() == JS::MapTypeToTraceKind<T>::kind;
+    }
+
+    template<class T>
+    inline T* as() {
+        MOZ_ASSERT(is<T>());
+        return static_cast<T*>(this);
+    }
+
+    template <class T>
+    inline const T* as() const {
+        MOZ_ASSERT(is<T>());
+        return static_cast<const T*>(this);
+    }
+
 #ifdef DEBUG
     inline bool isAligned() const;
     void dump(FILE* fp) const;
diff --git a/js/src/jsapi.cpp b/js/src/jsapi.cpp
index c0f0e61cc..cd370e42c 100644
--- a/js/src/jsapi.cpp
+++ b/js/src/jsapi.cpp
@@ -7040,7 +7040,9 @@ JS::CaptureCurrentStack(JSContext* cx, JS::MutableHandleObject stackp,
 {
     AssertHeapIsIdle(cx);
     CHECK_REQUEST(cx);
-    MOZ_RELEASE_ASSERT(cx->compartment());
+    if (!cx->compartment()) {
+      return false;
+    }
 
     JSCompartment* compartment = cx->compartment();
     Rooted<SavedFrame*> frame(cx);