Monomorphic prototype failures should be reserved for already-seen keys.

test/mjsunit/regress/regress-358088.js

Index: test/mjsunit/regress/regress-358088.js
diff --git a/test/mjsunit/regress/regress-358088.js b/test/mjsunit/regress/regress-358088.js
new file mode 100644
index 0000000000000000000000000000000000000000..222bba60d1cf3c1e5fa58fc3e6e2db5297da0f4f
--- /dev/null
+++ b/test/mjsunit/regress/regress-358088.js
@@ -0,0 +1,18 @@
+// Copyright 2014 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+function f(a) {
+  a[a.length] = 1;
+}
+
+function g(a, i, v) {
+  a[i] = v;
+}
+
+f([]);    // f KeyedStoreIC goes to 1.GROW
+o = {};
+g(o);     // We've added property "undefined" to o
+
+o = {};   // A transition on property "undefined" exists from {}
+f(o);     // Store should go generic.