Trace through const objects instead of spying on flow graph construction to find closure functions.…

runtime/vm/flow_graph_compiler.cc

Index: runtime/vm/flow_graph_compiler.cc
diff --git a/runtime/vm/flow_graph_compiler.cc b/runtime/vm/flow_graph_compiler.cc
index dd4adfdb9f8f0b9308d81c11fd740f33c621d8eb..b0004ca4ce8b5191ecb4bcc60099b232c7a09055 100644
--- a/runtime/vm/flow_graph_compiler.cc
+++ b/runtime/vm/flow_graph_compiler.cc
@@ -70,7 +70,6 @@ DECLARE_FLAG(bool, use_field_guards);
 DECLARE_FLAG(bool, use_cha_deopt);
 DECLARE_FLAG(bool, use_osr);
 DECLARE_FLAG(bool, warn_on_javascript_compatibility);
-DECLARE_FLAG(bool, precompile_collect_closures);
 DECLARE_FLAG(bool, print_stop_message);
 DECLARE_FLAG(bool, lazy_dispatchers);
 DECLARE_FLAG(bool, interpret_irregexp);
@@ -111,7 +110,6 @@ static void PrecompilationModeHandler(bool value) {
     FLAG_lazy_dispatchers = false;
     FLAG_interpret_irregexp = true;
     FLAG_enable_mirrors = false;
-    FLAG_precompile_collect_closures = true;
     FLAG_link_natives_lazily = true;
     FLAG_fields_may_be_reset = true;
     FLAG_allow_absolute_addresses = false;