Fix terrible interaction with code flushing.

src/compiler.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler.h"
 
 #include <algorithm>
 
 #include "src/ast-numbering.h"
 #include "src/bootstrapper.h"
@@ skipping 687 matching lines @@
       if (FLAG_trace_opt) {
         PrintF("[found optimized code for ");
         function->ShortPrint();
         if (!osr_ast_id.IsNone()) {
           PrintF(" at OSR AST id %d", osr_ast_id.ToInt());
         }
         PrintF("]\n");
       }
       FixedArray* literals = shared->GetLiteralsFromOptimizedCodeMap(index);
       if (literals != NULL) function->set_literals(literals);
-      return Handle<Code>(shared->GetCodeFromOptimizedCodeMap(index));
+      Code* code = shared->GetCodeFromOptimizedCodeMap(index);
+      DCHECK(!code->marked_for_deoptimization());
+      DCHECK(function->shared()->is_compiled());
+      return Handle<Code>(code);
     }
   }
   return MaybeHandle<Code>();
 }
 
 
 static void InsertCodeIntoOptimizedCodeMap(CompilationInfo* info) {
   Handle<Code> code = info->code();
   if (code->kind() != Code::OPTIMIZED_FUNCTION) return;  // Nothing to do.
 
@@ skipping 849 matching lines @@
 
 
 #if DEBUG
 void CompilationInfo::PrintAstForTesting() {
   PrintF("--- Source from AST ---\n%s\n",
          PrettyPrinter(isolate(), zone()).PrintProgram(function()));
 }
 #endif
 }  // namespace internal
 }  // namespace v8