anchor.diff:      Source source = addSource(code);
       CompilationUnit unit = await _computeResolvedUnit(source);
       // v
  -    DartType stringType = typeProvider.stringType;
       FormalParameter vParameter = EngineTestCase.findNode(
           unit, code, "v)", (node) => node is SimpleFormalParameter);
  -    expect(vParameter.identifier.propagatedType, same(stringType));
  -    expect(vParameter.identifier.staticType, same(typeProvider.objectType));
  +    expect(vParameter.identifier.propagatedType, typeProvider.stringType);
  +    expect(vParameter.identifier.staticType, typeProvider.objectType);
       SimpleIdentifier vIdentifier = EngineTestCase.findNode(
           unit, code, "v;", (node) => node is SimpleIdentifier);
  -    expect(vIdentifier.propagatedType, same(stringType));
  +    expect(vIdentifier.propagatedType, typeProvider.stringType);
     }
   
     test_Future_then() async {
  
positive.code:       VariableDeclarationStatement statement =
            statements[0] as VariableDeclarationStatement;
        SimpleIdentifier variableName = statement.variables.variables[0].name;
        expect(variableName.staticType, same(typeProvider.dynamicType));
        expect(variableName.propagatedType, same(typeProvider.intType));
      }
      // Type of 'v' in reference.
      {
        ReturnStatement statement = statements[1] as ReturnStatement;
        SimpleIdentifier variableName = statement.expression as SimpleIdentifier;
        expect(variableName.propagatedType, same(typeProvider.intType));
      }
    }
  
  
negative.code:     Source source = addSource(code);
      CompilationUnit unit = await _computeResolvedUnit(source);
      // k
      FormalParameter kParameter = EngineTestCase.findNode(
          unit, code, "k, ", (node) => node is SimpleFormalParameter);
      expect(kParameter.identifier.propagatedType, typeProvider.intType);
      SimpleIdentifier kIdentifier = EngineTestCase.findNode(
          unit, code, "k;", (node) => node is SimpleIdentifier);
      expect(kIdentifier.propagatedType, typeProvider.intType);
      expect(kIdentifier.staticType, typeProvider.dynamicType);
      // v
      FormalParameter vParameter = EngineTestCase.findNode(
          unit, code, "v)", (node) => node is SimpleFormalParameter);
      expect(vParameter.identifier.propagatedType, typeProvider.stringType);
      SimpleIdentifier vIdentifier = EngineTestCase.findNode(
          unit, code, "v;", (node) => node is SimpleIdentifier);
      expect(vIdentifier.propagatedType, typeProvider.stringType);
      expect(vIdentifier.staticType, typeProvider.dynamicType);
    }
  
    test_functionExpression_asInvocationArgument_fromInferredInvocation() async {
  