Make assertion scopes thread safe.

src/ia32/assembler-ia32-inl.h

Index: src/ia32/assembler-ia32-inl.h
diff --git a/src/ia32/assembler-ia32-inl.h b/src/ia32/assembler-ia32-inl.h
index cccacf78208e90c0ad1806e9759138721f8b0712..2a0c920936b756069860c8507b1eb8364ac95a7c 100644
--- a/src/ia32/assembler-ia32-inl.h
+++ b/src/ia32/assembler-ia32-inl.h
@@ -333,8 +333,7 @@ Immediate::Immediate(Handle<Object> handle) {
 #ifdef DEBUG
   Isolate* isolate = Isolate::Current();
 #endif
-  ALLOW_HANDLE_DEREF(isolate,
-                     "using and embedding raw address, heap object check");
+  AllowDeferredHandleDereference using_raw_address;
   // Verify all Objects referred by code are NOT in new space.
   Object* obj = *handle;
   ASSERT(!isolate->heap()->InNewSpace(obj));
@@ -368,7 +367,7 @@ void Assembler::emit(uint32_t x) {
 
 
 void Assembler::emit(Handle<Object> handle) {
-  ALLOW_HANDLE_DEREF(isolate(), "heap object check");
+  AllowDeferredHandleDereference heap_object_check;
   // Verify all Objects referred by code are NOT in new space.
   Object* obj = *handle;
   ASSERT(!isolate()->heap()->InNewSpace(obj));
@@ -395,7 +394,7 @@ void Assembler::emit(uint32_t x, RelocInfo::Mode rmode, TypeFeedbackId id) {
 void Assembler::emit(Handle<Code> code,
                      RelocInfo::Mode rmode,
                      TypeFeedbackId id) {
-  ALLOW_HANDLE_DEREF(isolate(), "embedding raw address");
+  AllowDeferredHandleDereference embedding_raw_address;
   emit(reinterpret_cast<intptr_t>(code.location()), rmode, id);
 }