Mark maps as unstable if their instances potentially transition away.

test/mjsunit/regress/regress-omit-checks.js

Index: test/mjsunit/regress/regress-omit-checks.js
diff --git a/test/mjsunit/compiler/phi-representations.js b/test/mjsunit/regress/regress-omit-checks.js
similarity index 79%
copy from test/mjsunit/compiler/phi-representations.js
copy to test/mjsunit/regress/regress-omit-checks.js
index 6d11bb0d8ea714daae5e5942b750fa9d3601439b..e5d50749888078e77259863534964da50bd2abab 100644
--- a/test/mjsunit/compiler/phi-representations.js
+++ b/test/mjsunit/regress/regress-omit-checks.js
@@ -27,30 +27,29 @@
 
 // Flags: --allow-natives-syntax
 
-function ar() {
-  var r = undefined;
-  var f = 1;
-  while (f--) {
-    r = (typeof r === 'undefined') ? 0.1 : r;
-  };
-  return (r - r);
+var a = {x:1};
+var a_deprecate = {x:1};
+a_deprecate.x = 1.5;
+function create() {
+  return {__proto__:a, y:1};
 }
+var b1 = create();
+var b2 = create();
+var b3 = create();
+var b4 = create();
 
-assertEquals(0, ar());
-assertEquals(0, ar());
-%OptimizeFunctionOnNextCall(ar);
-assertEquals(0, ar());
-
-function ar2() {
-  var r = undefined;
-  var f = 1;
-  while (f--) {
-    r = r === undefined ? 0.1 : r;
-  };
-  return (r - r);
+function set(b) {
+  b.x = 5;
+  b.z = 10;
 }
 
-assertEquals(0, ar2());
-assertEquals(0, ar2());
-%OptimizeFunctionOnNextCall(ar2);
-assertEquals(0, ar2());
+set(b1);
+set(b2);
+%OptimizeFunctionOnNextCall(set);
+set(b3);
+var called = false;
+a.x = 1.5;
+Object.defineProperty(a, "z", {set:function(v) { called = true; }});
+set(b4);
+assertTrue(called);
+assertEquals(undefined, b4.z);