anchor.diff:  
   class SsaOptimizedCodeGenerator extends SsaCodeGenerator {
     SsaOptimizedCodeGenerator(backend, work, parameters, parameterNames)
  -    : super(backend, work, parameters, parameterNames);
  +    : super(backend, work, parameters, parameterNames) {
  +    // Declare the parameter names only for the optimized version. The
  +    // unoptimized version has different parameters.
  +    parameterNames.forEach((Element element, String name) {
  +      declaredVariables.add(name);
  +    });
  +  }
   
     int maxBailoutParameters;
   
  
positive.code:     // call site for non-complex bailout methods.
      newParameters.add('state');
  
      if (!propagator.hasComplexTypeGuards) {
        propagator.firstTypeGuard.block.first = savedFirstInstruction;
        for (HInstruction input in propagator.firstTypeGuard.inputs) {
  
negative.code:     equalsNullElement = interceptors.getEqualsNullInterceptor();
      boolifiedEqualsNullElement =
          interceptors.getBoolifiedVersionOf(equalsNullElement);
    }
  
    abstract visitTypeGuard(HTypeGuard node);
  