anchor.diff:      // class A {
       //   m() {}
       // }
  -    LibraryElementImpl library =
  -        ElementFactory.library(createAnalysisContext(), "lib");
  +    LibraryElementImpl library = _newLibrary();
       ClassElementImpl classA = ElementFactory.classElement2("A");
       String methodName = "m";
       MethodElement method = ElementFactory.methodElement(methodName, null);
  
positive.code:   void test_lookUpGetter_undeclared() {
      // class A {
      // }
      LibraryElementImpl library =
          ElementFactory.library(createAnalysisContext(), "lib");
      ClassElementImpl classA = ElementFactory.classElement2("A");
      (library.definingCompilationUnit as CompilationUnitElementImpl).types =
          <ClassElement>[classA];
  
negative.code:   void test_lookUpSetter_undeclared() {
      // class A {
      // }
      LibraryElementImpl library = _newLibrary();
      ClassElementImpl classA = ElementFactory.classElement2("A");
      (library.definingCompilationUnit as CompilationUnitElementImpl).types =
          <ClassElement>[classA];
  