AssemblerBase does not need remember a Zone. Fix this.

src/assembler.cc

Index: src/assembler.cc
diff --git a/src/assembler.cc b/src/assembler.cc
index 827a4abf7c0abd03f8a72a90a630a09ea4dde853..d4c49ddd459ef744b0b2230557f967ac681df434 100644
--- a/src/assembler.cc
+++ b/src/assembler.cc
@@ -106,10 +106,9 @@ const char* const RelocInfo::kFillerCommentString = "DEOPTIMIZATION PADDING";
 // -----------------------------------------------------------------------------
 // Implementation of AssemblerBase
 
-AssemblerBase::AssemblerBase(Isolate* isolate, Zone* zone)
+AssemblerBase::AssemblerBase(Isolate* isolate)
     : isolate_(isolate),
-      jit_cookie_(0),
-      zone_(zone) {
+      jit_cookie_(0) {
   if (FLAG_mask_constants_with_cookie && isolate != NULL)  {
     jit_cookie_ = V8::RandomPrivate(isolate);
   }