Delete HAbnormalExit. It does more harm than good.

src/hydrogen-environment-liveness.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 145 matching lines @@
     case HValue::kEnterInlined: {
       // Those environment values are live that are live at any return
       // target block. Here we make use of the fact that the end of an
       // inline sequence always looks like this: HLeaveInlined, HSimulate,
       // HGoto (to return_target block), with no environment lookups in
       // between (see ASSERTs above).
       HEnterInlined* enter = HEnterInlined::cast(instr);
       live->Clear();
       for (int i = 0; i < enter->return_targets()->length(); ++i) {
         int return_id = enter->return_targets()->at(i)->block_id();
-        // When an AbnormalExit is involved, it can happen that the return
-        // target block doesn't actually exist.
-        if (return_id < live_at_block_start_.length()) {
-          live->Union(*live_at_block_start_[return_id]);
-        }
+        live->Union(*live_at_block_start_[return_id]);
       }
       last_simulate_ = NULL;
       break;
     }
     case HValue::kSimulate:
       last_simulate_ = HSimulate::cast(instr);
       went_live_since_last_simulate_.Clear();
       break;
     default:
       break;
@@ skipping 58 matching lines @@
     ZapEnvironmentSlotsInSuccessors(block, &live);
   }
 
   // Finally, remove the HEnvironment{Bind,Lookup} markers.
   for (int i = 0; i < markers_.length(); ++i) {
     markers_[i]->DeleteAndReplaceWith(NULL);
   }
 }
 
 } }  // namespace v8::internal