diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/jaeger/bug649593.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/jaeger/bug649593.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,10 @@
+function RunSingleBenchmark(data) {
+    if (data == null)
+        return { runs: 0, elapsed: 0 };
+    data.runs += 10;
+    return data;
+}
+var data;
+data = RunSingleBenchmark(data);
+data = RunSingleBenchmark(data);
+assertEq(data.runs, 10);
\ No newline at end of file