Maintain a FixedArray for the optimized code map.

src/debug/debug.cc

Index: src/debug/debug.cc
diff --git a/src/debug/debug.cc b/src/debug/debug.cc
index b680fdefd72e7070a58b2fb7530d05d424e2cda6..73182b1346eab809bf257cdc1594aae0826d7e31 100644
--- a/src/debug/debug.cc
+++ b/src/debug/debug.cc
@@ -1311,7 +1311,7 @@ bool Debug::PrepareFunctionForBreakPoints(Handle<SharedFunctionInfo> shared) {
   {
     SharedFunctionInfo::Iterator iterator(isolate_);
     while (SharedFunctionInfo* shared = iterator.Next()) {
-      if (!shared->optimized_code_map()->IsSmi()) {
+      if (!shared->OptimizedCodeMapIsCleared()) {
         shared->ClearOptimizedCodeMap();
       }
     }