anchor.diff:    test_staticVariable() async {
       await assertErrorsInCode(r'''
   class A {
  -  static int x;
  +  static int x = 7;
   }
   f(var y) {
     if (y is String) {
  
positive.code: }
  
  class C {
    A a;
  }
  
  f(C c) {
  
negative.code: }
  
  class C {
    A a = A();
  }
  
  f(C c) {
  