Introduce --zap-cpp-pointers (off by default)

src/type-info.cc

Index: src/type-info.cc
diff --git a/src/type-info.cc b/src/type-info.cc
index ee646afb749f18db2fdba43109c660811ea05ce1..ab9c594f98a566321786119e62ff69347efb3de3 100644
--- a/src/type-info.cc
+++ b/src/type-info.cc
@@ -490,21 +490,24 @@ void TypeFeedbackOracle::GetRelocInfos(Handle<Code> code,
 
 void TypeFeedbackOracle::CreateDictionary(Handle<Code> code,
                                           ZoneList<RelocInfo>* infos) {
-  AllowHeapAllocation allocation_allowed;
-  Code* old_code = *code;
+  AllowHeapAllocation will_relocate_manually;
+  // Store an (aligned) Address, so this doesn't look like a raw heap pointer
+  // to verification tools scanning the stack.
+  Address old_code_address = code->address();
   dictionary_ = UnseededNumberDictionary::New(isolate(), infos->length());
-  RelocateRelocInfos(infos, old_code, *code);
+  RelocateRelocInfos(infos, old_code_address, code->address());
 }
 
-
 void TypeFeedbackOracle::RelocateRelocInfos(ZoneList<RelocInfo>* infos,
-                                            Code* old_code,
-                                            Code* new_code) {
+                                            Address old_code_address,
+                                            Address new_code_address) {
+  intptr_t delta = new_code_address - old_code_address;
+  if (delta == 0) return;
+  Code* new_code = Code::cast(HeapObject::FromAddress(new_code_address));
   for (int i = 0; i < infos->length(); i++) {
     RelocInfo* info = &(*infos)[i];
     info->set_host(new_code);
-    info->set_pc(new_code->instruction_start() +
-                 (info->pc() - old_code->instruction_start()));
+    info->set_pc(info->pc() + delta);
   }
 }