Do not go to slow mode and back to fast in initializer blocks.

src/ast.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 108 matching lines @@
                        Expression* target,
                        Expression* value,
                        int pos)
     : Expression(isolate),
       op_(op),
       target_(target),
       value_(value),
       pos_(pos),
       binary_operation_(NULL),
       assignment_id_(GetNextId(isolate)),
-      block_start_(false),
-      block_end_(false),
       is_monomorphic_(false) { }
 
 
 Token::Value Assignment::binary_op() const {
   switch (op_) {
     case Token::ASSIGN_BIT_OR: return Token::BIT_OR;
     case Token::ASSIGN_BIT_XOR: return Token::BIT_XOR;
     case Token::ASSIGN_BIT_AND: return Token::BIT_AND;
     case Token::ASSIGN_SHL: return Token::SHL;
     case Token::ASSIGN_SAR: return Token::SAR;
@@ skipping 991 matching lines @@
     OS::SNPrintF(buffer, "%d", Smi::cast(*handle_)->value());
     str = arr;
   } else {
     str = DoubleToCString(handle_->Number(), buffer);
   }
   return FACTORY->NewStringFromAscii(CStrVector(str));
 }
 
 
 } }  // namespace v8::internal