Get rid of unused field has_compiled_code_ from the Isolate structure.

runtime/vm/precompiler.cc

 // Copyright (c) 2015, 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/precompiler.h"
 
 #include "vm/aot_optimizer.h"
 #include "vm/assembler.h"
 #include "vm/ast_printer.h"
 #include "vm/branch_optimizer.h"
@@ skipping 3479 matching lines @@
         pipeline->FinalizeCompilation(flow_graph);
       }
       {
 #ifndef PRODUCT
         TimelineDurationScope tds(thread(), compiler_timeline,
                                   "FinalizeCompilation");
 #endif  // !PRODUCT
         ASSERT(thread()->IsMutatorThread());
         FinalizeCompilation(&assembler, &graph_compiler, flow_graph);
       }
-      // Mark that this isolate now has compiled code.
-      isolate()->set_has_compiled_code(true);
       // Exit the loop and the function with the correct result value.
       is_compiled = true;
       done = true;
     } else {
       // We bailed out or we encountered an error.
       const Error& error = Error::Handle(thread()->sticky_error());
 
       if (error.raw() == Object::branch_offset_error().raw()) {
         // Compilation failed due to an out of range branch offset in the
         // assembler. We try again (done = false) with far branches enabled.
@@ skipping 143 matching lines @@
 
   ASSERT(FLAG_precompiled_mode);
   const bool optimized = function.IsOptimizable();  // False for natives.
   DartPrecompilationPipeline pipeline(zone, field_type_map);
   return PrecompileFunctionHelper(precompiler, &pipeline, function, optimized);
 }
 
 #endif  // DART_PRECOMPILER
 
 }  // namespace dart