Delete HAbnormalExit. It does more harm than good.

src/x64/lithium-x64.cc

Index: src/x64/lithium-x64.cc
diff --git a/src/x64/lithium-x64.cc b/src/x64/lithium-x64.cc
index 57938b213fc634c8b0feffbedbfea27b186111fe..25a300553eb8ee9a12cfc30127b5171048871059 100644
--- a/src/x64/lithium-x64.cc
+++ b/src/x64/lithium-x64.cc
@@ -1789,13 +1789,6 @@ LInstruction* LChunkBuilder::DoBoundsCheckBaseIndexInformation(
 }
 
 
-LInstruction* LChunkBuilder::DoAbnormalExit(HAbnormalExit* instr) {
-  // The control instruction marking the end of a block that completed
-  // abruptly (e.g., threw an exception).  There is nothing specific to do.
-  return NULL;
-}
-
-
 LInstruction* LChunkBuilder::DoThrow(HThrow* instr) {
   LOperand* value = UseFixed(instr->value(), rax);
   return MarkAsCall(new(zone()) LThrow(value), instr);