Merge up to bleeding_edge r7201 to isolates branch.

src/x64/assembler-x64.cc

Index: src/x64/assembler-x64.cc
diff --git a/src/x64/assembler-x64.cc b/src/x64/assembler-x64.cc
index bfca467dde48f5df0c27814db13ba6dcca6ed2c5..a324c81a485a974c940560756badd5f9a4e7d682 100644
--- a/src/x64/assembler-x64.cc
+++ b/src/x64/assembler-x64.cc
@@ -337,7 +337,9 @@ static void InitCoverageLog();
 #endif
 
 Assembler::Assembler(void* buffer, int buffer_size)
-    : code_targets_(100), positions_recorder_(this) {
+    : code_targets_(100),
+      positions_recorder_(this),
+      emit_debug_code_(FLAG_debug_code) {
   Isolate* isolate = Isolate::Current();
   if (buffer == NULL) {
     // Do our own buffer management.
@@ -3118,7 +3120,7 @@ void Assembler::RecordRelocInfo(RelocInfo::Mode rmode, intptr_t data) {
       Serializer::TooLateToEnableNow();
     }
 #endif
-    if (!Serializer::enabled() && !FLAG_debug_code) {
+    if (!Serializer::enabled() && !emit_debug_code()) {
       return;
     }
   }