Use a class field instead of global FLAG_debug_code in assember and

src/arm/assembler-arm.cc

Index: src/arm/assembler-arm.cc
diff --git a/src/arm/assembler-arm.cc b/src/arm/assembler-arm.cc
index 54b244649d74587ac75e3e5ec5150a727772dbdb..e58d968c5fb4bf00644abb652cf92bcf16c09279 100644
--- a/src/arm/assembler-arm.cc
+++ b/src/arm/assembler-arm.cc
@@ -271,7 +271,8 @@ static byte* spare_buffer_ = NULL;
 
 Assembler::Assembler(void* buffer, int buffer_size)
     : positions_recorder_(this),
-      allow_peephole_optimization_(false) {
+      allow_peephole_optimization_(false),
+      emit_debug_code_(FLAG_debug_code) {
   allow_peephole_optimization_ = FLAG_peephole_optimization;
   if (buffer == NULL) {
     // Do our own buffer management.
@@ -2665,7 +2666,7 @@ 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;
       }
     }