Allow uncacheable identifiers to go generic.

test/mjsunit/regress/regress-store-uncacheable.js

Index: test/mjsunit/regress/regress-store-uncacheable.js
diff --git a/test/mjsunit/regress/regress-crbug-173974.js b/test/mjsunit/regress/regress-store-uncacheable.js
similarity index 96%
copy from test/mjsunit/regress/regress-crbug-173974.js
copy to test/mjsunit/regress/regress-store-uncacheable.js
index 905bd6058a0ad0fe2ebe10e4c7dafbe9945cbe3b..e9c9fc25b49c95293a5c0acea0bea8d073a79e0e 100644
--- a/test/mjsunit/regress/regress-crbug-173974.js
+++ b/test/mjsunit/regress/regress-store-uncacheable.js
@@ -28,9 +28,13 @@
 // Flags: --allow-natives-syntax
 
 function f() {
-  var count = "";
-  count[0] --;
+  var o = {};
+  o["<abc>"] = 123;
 }
+
+f();
+f();
 f();
 %OptimizeFunctionOnNextCall(f);
 f();
+assertOptimized(f);