Fix optimizations on static fields in precompiled code.

runtime/vm/flow_graph_optimizer.cc

Index: runtime/vm/flow_graph_optimizer.cc
diff --git a/runtime/vm/flow_graph_optimizer.cc b/runtime/vm/flow_graph_optimizer.cc
index 22ba02f3634f57a2e3e94b7bd309edfa4f08b701..b698a6960a7a1258f1b00ee84321f48154a33791 100644
--- a/runtime/vm/flow_graph_optimizer.cc
+++ b/runtime/vm/flow_graph_optimizer.cc
@@ -55,6 +55,7 @@ DECLARE_FLAG(bool, trace_cha);
 DECLARE_FLAG(bool, trace_field_guards);
 DECLARE_FLAG(bool, trace_type_check_elimination);
 DECLARE_FLAG(bool, warn_on_javascript_compatibility);
+DECLARE_FLAG(bool, fields_may_be_reset);
 
 // Quick access to the current isolate and zone.
 #define I (isolate())
@@ -5654,7 +5655,9 @@ class Place : public ValueObject {
   }
 
   bool IsFinalField() const {
-    return (kind() == kField) && field().is_final();
+    return (kind() == kField)
+        && field().is_final()
+        && (!field().is_static() || !FLAG_fields_may_be_reset);

[srdjan, 2015/12/03 16:57:56]

IMO, the flag does not belong here, the test is for IsFinalField. I suggest
renaming the test method to something like IsImmutableField and add comment what
is going on.

[rmacnak, 2015/12/03 21:09:11]

Ditto.

[Florian Schneider, 2015/12/04 11:36:54]

Done.

   }
 
   intptr_t Hashcode() const {