anchor.diff:  
   import '../parser.dart' show noLength;
   
  -import '../problems.dart' show internalProblem, unexpected;
  +import '../problems.dart' show unexpected;
   
   import '../deprecated_problems.dart' show deprecated_inputError;
   
  
positive.code:   KernelFunctionBuilder get actualOrigin;
  
    void set body(Statement newBody) {
      if (newBody != null) {
        if (isAbstract) {
          return internalProblem(messageInternalProblemBodyOnAbstractMethod,
              newBody.fileOffset, fileUri);
        }
      }
      actualBody = newBody;
      if (function != null) {
        // A forwarding semi-stub is a method that is abstract in the source code,
  
negative.code: 
  import '../messages.dart'
      show
          messageNonInstanceTypeVariableUse,
          messagePatchDeclarationMismatch,
          messagePatchDeclarationOrigin,
  