Track JS allocations as they arrive with no affection on performance when tracking is switched off

src/assembler.cc

Index: src/assembler.cc
diff --git a/src/assembler.cc b/src/assembler.cc
index 6581aa1305a459fdc8c90b31d0a9faabf9f78169..d44f1f4fba58fb5b1a2775f328e9d07b13588374 100644
--- a/src/assembler.cc
+++ b/src/assembler.cc
@@ -117,6 +117,7 @@ AssemblerBase::AssemblerBase(Isolate* isolate, void* buffer, int buffer_size)
       jit_cookie_(0),
       enabled_cpu_features_(0),
       emit_debug_code_(FLAG_debug_code),
+      emit_allocations_tracking_code_(false),
       predictable_code_size_(false) {
   if (FLAG_mask_constants_with_cookie && isolate != NULL)  {
     jit_cookie_ = isolate->random_number_generator()->NextInt();
@@ -1335,6 +1336,14 @@ ExternalReference ExternalReference::address_of_the_hole_nan() {
 }
 
 
+ExternalReference ExternalReference::record_object_allocation_function(
+  Isolate* isolate) {
+  return ExternalReference(
+      Redirect(isolate,
+               FUNCTION_ADDR(HeapProfiler::RecordObjectAllocationFromMasm)));
+}
+
+
 #ifndef V8_INTERPRETED_REGEXP
 
 ExternalReference ExternalReference::re_check_stack_guard_state(