--- a/js/public/Utility.h
+++ b/js/public/Utility.h
@@ -503,16 +503,27 @@ static JS_ALWAYS_INLINE void
 js_delete(T *p)
 {
     if (p) {
         p->~T();
         js_free(p);
     }
 }
 
+template<class T>
+static JS_ALWAYS_INLINE void
+js_delete_poison(T *p)
+{
+    if (p) {
+        p->~T();
+        memset(p, 0x3B, sizeof(T));
+        js_free(p);
+    }
+}
+
 template <class T>
 static JS_ALWAYS_INLINE T *
 js_pod_malloc()
 {
     return (T *)js_malloc(sizeof(T));
 }
 
 template <class T>

--- a/js/src/jscntxt.cpp
+++ b/js/src/jscntxt.cpp
@@ -426,17 +426,17 @@ js::DestroyContext(JSContext *cx, Destro
 
         JS::PrepareForFullGC(rt);
         GC(rt, GC_NORMAL, JS::gcreason::LAST_CONTEXT);
     } else if (mode == DCM_FORCE_GC) {
         JS_ASSERT(!rt->isHeapBusy());
         JS::PrepareForFullGC(rt);
         GC(rt, GC_NORMAL, JS::gcreason::DESTROY_CONTEXT);
     }
-    js_delete(cx);
+    js_delete_poison(cx);
 }
 
 bool
 AutoResolving::alreadyStartedSlow() const
 {
     JS_ASSERT(link);
     AutoResolving *cursor = link;
     do {