Merge two static_final_field tests and rewrite a negative test to a multi-test

tests/language/scope_variable_test.dart

Index: tests/language/scope_variable_test.dart
diff --git a/tests/language/scope_variable_test.dart b/tests/language/scope_variable_test.dart
index 1437de64dabcf928766ce409c0e931c96dac8b56..58ae9105d586fda90bc8f48ed2c8586a67ad3c83 100644
--- a/tests/language/scope_variable_test.dart
+++ b/tests/language/scope_variable_test.dart
@@ -21,11 +21,11 @@ void testShadowingScope() {
   var a = "Test";
   {
     var a;
-    Expect.equals(true, a == null);
+    Expect.isNull(a);
     a = "a";
-    Expect.equals(true, a == "a");
+    Expect.equals(a, "a");
   }
-  Expect.equals(true, a == "Test");
+  Expect.equals(a, "Test");
 }
 
 int testShadowingAfterUse() {