diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/debug/cross-context-1.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/debug/cross-context-1.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,20 @@
+// frame.eval can evaluate code in a frame pushed in another context. Bug 749697.
+
+// In other words, the debugger can see all frames on the stack, even though
+// each frame is attached to a particular JSContext and multiple JSContexts may
+// have frames on the stack.
+
+var g = newGlobal();
+g.eval('function f(a) { debugger; evaluate("debugger;", {newContext: true}); }');
+
+var dbg = new Debugger(g);
+var hits = 0;
+dbg.onDebuggerStatement = function (frame1) {
+    dbg.onDebuggerStatement = function (frame2) {
+        assertEq(frame1.eval("a").return, 31);
+        hits++;
+    };
+};
+
+g.f(31);
+assertEq(hits, 1);