[runtime][ic] Constant field tracking support.

test/mjsunit/track-fields.js

Index: test/mjsunit/track-fields.js
diff --git a/test/mjsunit/track-fields.js b/test/mjsunit/track-fields.js
index 4da1ab5d2279f85e7a8c2268e4a572d6c474e386..7804fffec0392fce98823db0aaef9accb277be75 100644
--- a/test/mjsunit/track-fields.js
+++ b/test/mjsunit/track-fields.js
@@ -263,6 +263,9 @@ assertEquals(100, o20.dbl);
 
 function attr_mismatch_obj(v, writable) {
   var o = {};
+  // Assign twice to make the field non-constant.
+  // TODO(ishell): update test once constant field tracking is done.
+  o.some_value = 0;
   o.some_value = v;
   Object.defineProperty(o, "second_value", {value:10, writable:writable});
   return o;