Do not trigger optimization on functions that are not optimizable (e.g. natives).

runtime/vm/intermediate_language_x64.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_X64.
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/intermediate_language.h"
 
 #include "lib/error.h"
@@ skipping 37 matching lines @@
   ASSERT(result == RAX);
   if (!compiler->is_optimizing()) {
     __ Comment("Check function counter");
     // Count only in unoptimized code.
     // TODO(srdjan): Replace the counting code with a type feedback
     // collection and counting stub.
     const Function& function =
           Function::ZoneHandle(compiler->parsed_function().function().raw());
     __ LoadObject(temp, function);
     __ incq(FieldAddress(temp, Function::usage_counter_offset()));
-    if (FlowGraphCompiler::CanOptimize()) {
+    if (FlowGraphCompiler::CanOptimize() &&
+        compiler->parsed_function().function().is_optimizable()) {
       // Do not optimize if usage count must be reported.
       __ cmpq(FieldAddress(temp, Function::usage_counter_offset()),
           Immediate(FLAG_optimization_counter_threshold));
       Label not_yet_hot, already_optimized;
       __ j(LESS, &not_yet_hot, Assembler::kNearJump);
       __ j(GREATER, &already_optimized, Assembler::kNearJump);
       __ pushq(result);  // Preserve result.
       __ pushq(temp);  // Argument for runtime: function to optimize.
       __ CallRuntime(kOptimizeInvokedFunctionRuntimeEntry);
       __ popq(temp);  // Remove argument.
@@ skipping 2179 matching lines @@
     __ j(ABOVE_EQUAL, deopt);
   }
 }
 
 
 }  // namespace dart
 
 #undef __
 
 #endif  // defined TARGET_ARCH_X64