Bug 762473 - Don't apply non-reentrant-closure optimization when the scope is extensible (r=dvander)

js/src/frontend/BytecodeCompiler.cpp

@@ -34,6 +34,13 @@ MarkInnerAndOuterFunctions(JSContext *cx, JSScript* script_)
         JSScript *outer = worklist.back();
         worklist.popBack();
 
+        /*
+         * If outer has an extensible scope, its slots may be resized which
+         * will invalidate nesting->varArray/argArray.
+         */
+        if (outer->funHasExtensibleScope)
+            continue;
+
         if (outer->hasObjects()) {
             ObjectArray *arr = outer->objects();