[turbofan] Break dependency on RegisterAllocationData from Merge.

src/compiler/live-range-separator.cc

Index: src/compiler/live-range-separator.cc
diff --git a/src/compiler/live-range-separator.cc b/src/compiler/live-range-separator.cc
index a80259535a955a2c1cc0323cb84a8ae26808dca1..f34b0d41ce5a3e69a3b66b9e283d7405df936022 100644
--- a/src/compiler/live-range-separator.cc
+++ b/src/compiler/live-range-separator.cc
@@ -153,7 +153,9 @@ void LiveRangeMerger::Merge() {
     }
     TopLevelLiveRange *splinter_parent = range->splintered_from();
 
-    splinter_parent->Merge(range, data());
+    int to_remove = range->vreg();
+    splinter_parent->Merge(range, data()->allocation_zone());
+    data()->live_ranges()[to_remove] = nullptr;
   }
 }