[turbofan] Break dependency on RegisterAllocationData from Merge.

src/compiler/register-allocator.cc

Index: src/compiler/register-allocator.cc
diff --git a/src/compiler/register-allocator.cc b/src/compiler/register-allocator.cc
index f6c339234abb4d8a143d4858134e16fa272d5dac..8438b5534278dc186403848991f26017ee305180 100644
--- a/src/compiler/register-allocator.cc
+++ b/src/compiler/register-allocator.cc
@@ -887,13 +887,10 @@ void TopLevelLiveRange::UpdateSpillRangePostMerge(TopLevelLiveRange* merged) {
 }
 
 
-void TopLevelLiveRange::Merge(TopLevelLiveRange* other,
-                              RegisterAllocationData* data) {
+void TopLevelLiveRange::Merge(TopLevelLiveRange* other, Zone* zone) {
   DCHECK(Start() < other->Start());
   DCHECK(other->splintered_from() == this);
 
-  data->live_ranges()[other->vreg()] = nullptr;
-
   LiveRange* last_other = other->last_child();
   LiveRange* last_me = last_child();
 
@@ -919,8 +916,7 @@ void TopLevelLiveRange::Merge(TopLevelLiveRange* other,
   // register allocation splitting.
   LiveRange* after = last_insertion_point_->next();
   if (last_insertion_point_->End() > other->Start()) {
-    LiveRange* new_after =
-        last_insertion_point_->SplitAt(other->Start(), data->allocation_zone());
+    LiveRange* new_after = last_insertion_point_->SplitAt(other->Start(), zone);
     new_after->set_spilled(last_insertion_point_->spilled());
     if (!new_after->spilled())
       new_after->set_assigned_register(