- Mark huge methods are not-optimizable.

runtime/vm/object.cc

Index: runtime/vm/object.cc
===================================================================
--- runtime/vm/object.cc	(revision 16586)
+++ runtime/vm/object.cc	(working copy)
@@ -40,6 +40,8 @@
     "instead of showing the corresponding interface names (e.g. \"String\")");
 DEFINE_FLAG(bool, trace_disabling_optimized_code, false,
     "Trace disabling optimized code.");
+DEFINE_FLAG(int, huge_method_cutoff, 20000,
+            "Huge method cutoff: Disables optimizations for huge methods.");
 DECLARE_FLAG(bool, trace_compiler);
 DECLARE_FLAG(bool, eliminate_type_checks);
 DECLARE_FLAG(bool, enable_type_checks);
@@ -3456,7 +3458,8 @@
 bool Function::is_optimizable() const {
   return OptimizableBit::decode(raw_ptr()->kind_tag_) &&
          (script() != Script::null()) &&
-         !is_native();
+         !is_native() &&
+         ((end_token_pos() - token_pos()) < FLAG_huge_method_cutoff);
 }