Fix handling of constant global variable assignments.

test/mjsunit/regress/regress-347904.js

Index: test/mjsunit/regress/regress-347904.js
diff --git a/test/mjsunit/regress/regress-crbug-346141.js b/test/mjsunit/regress/regress-347904.js
similarity index 55%
copy from test/mjsunit/regress/regress-crbug-346141.js
copy to test/mjsunit/regress/regress-347904.js
index 798b7704ec2cc0eb928966fdfe9f979d0fe51f94..1a27b054a4b89b8e8841c9311f1c155aea7ce4d7 100644
--- a/test/mjsunit/regress/regress-crbug-346141.js
+++ b/test/mjsunit/regress/regress-347904.js
@@ -2,10 +2,11 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --harmony-symbols
+// Flags: --allow-natives-syntax --stress-runs=2
 
-var s = Symbol()
-var o = {}
-o[s] = 2
-o[""] = 3
-Object.getOwnPropertySymbols(o)
+var v = /abc/;
+function f() {
+  v = 1578221999;
+};
+%OptimizeFunctionOnNextCall(f);
+f();