Disentangle assembler from isolate.

src/x64/macro-assembler-x64.cc

Index: src/x64/macro-assembler-x64.cc
diff --git a/src/x64/macro-assembler-x64.cc b/src/x64/macro-assembler-x64.cc
index d84b20fb7d8e7ec761df7692aab5989e682d77b8..5371afcdfef0a9a7893ca818215b62064cec29d1 100644
--- a/src/x64/macro-assembler-x64.cc
+++ b/src/x64/macro-assembler-x64.cc
@@ -6,6 +6,7 @@
 
 #include "src/base/bits.h"
 #include "src/base/division-by-constant.h"
+#include "src/base/utils/random-number-generator.h"
 #include "src/bootstrapper.h"
 #include "src/codegen.h"
 #include "src/counters.h"
@@ -20,15 +21,20 @@
 namespace v8 {
 namespace internal {
 
-MacroAssembler::MacroAssembler(Isolate* arg_isolate, void* buffer, int size,
+MacroAssembler::MacroAssembler(Isolate* isolate, void* buffer, int size,
                                CodeObjectRequired create_code_object)
-    : Assembler(arg_isolate, buffer, size),
+    : Assembler(isolate, buffer, size),
       generating_stub_(false),
       has_frame_(false),
-      root_array_available_(true) {
+      isolate_(isolate),
+      root_array_available_(true),
+      jit_cookie_(0) {
+  if (FLAG_mask_constants_with_cookie) {
+    jit_cookie_ = isolate->random_number_generator()->NextInt();
+  }
   if (create_code_object == CodeObjectRequired::kYes) {
     code_object_ =
-        Handle<Object>::New(isolate()->heap()->undefined_value(), isolate());
+        Handle<Object>::New(isolate_->heap()->undefined_value(), isolate_);
   }
 }