Make sure IfBuilder::Return clears the current block.

src/code-stubs-hydrogen.cc

 // Copyright 2012 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 168 matching lines @@
           HAdd::New(zone, context_, stack_parameter_count, amount));
       stack_pop_count->ChangeRepresentation(Representation::Integer32());
       stack_pop_count->ClearFlag(HValue::kCanOverflow);
     } else {
       int count = descriptor_->hint_stack_parameter_count_;
       stack_pop_count = AddInstruction(new(zone)
           HConstant(count, Representation::Integer32()));
     }
   }
 
-  if (!current_block()->IsFinished()) {
+  if (current_block() != NULL) {
     HReturn* hreturn_instruction = new(zone) HReturn(return_value,
                                                      context_,
                                                      stack_pop_count);
     current_block()->Finish(hreturn_instruction);
+    set_current_block(NULL);
   }
   return true;
 }
 
 
 template <class Stub>
 class CodeStubGraphBuilder: public CodeStubGraphBuilderBase {
  public:
   explicit CodeStubGraphBuilder(Stub* stub)
       : CodeStubGraphBuilderBase(Isolate::Current(), stub) {}
@@ skipping 463 matching lines @@
       ? graph()->GetConstant1()
       : graph()->GetConstantUndefined();
 }
 
 
 Handle<Code> CompareNilICStub::GenerateCode() {
   return DoGenerateCode(this);
 }
 
 } }  // namespace v8::internal