diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/debug/Frame-onPop-multiple-03.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/debug/Frame-onPop-multiple-03.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,36 @@
+// One Debugger's onPop handler can disable another Debugger.
+var g = newGlobal();
+var dbg1 = new Debugger(g);
+var dbg2 = new Debugger(g);
+
+var log;
+var frames = [];
+var firstPop = true;
+
+function handleEnter(frame) {
+    log += '(';
+    frames.push(frame);
+    frame.debugger = this;
+    frame.onPop = function handlePop(completion) {
+        log += ')';
+        assertEq(completion.return, 42);
+        if (firstPop) {
+            // We can't say which frame's onPop handler will get called first.
+            if (this == frames[0])
+                frames[1].debugger.enabled = false;
+            else
+                frames[0].debugger.enabled = false;
+        } else {
+            assertEq("second pop handler was called",
+                     "second pop handler should not be called");
+        }
+        firstPop = false;
+    };
+};
+
+dbg1.onEnterFrame = handleEnter;
+dbg2.onEnterFrame = handleEnter;
+
+log = '';
+assertEq(g.eval('40 + 2'), 42);
+assertEq(log, '(()');