Fixes for empty class and method bodies.

pkg/analyzer/test/services/data/stmt_tests.data

 >>>
 if (x &&
     y) {
   print('!');
 }
 <<<
 if (x && y) {
   print('!');
 }
 >>>
@@ skipping 103 matching lines @@
     new XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX();
 >>>
 main() {
   throw new FormatException("This is a long exception message that puts this over 80 columns.");
 }
 <<<
 main() {
   throw new FormatException(
       "This is a long exception message that puts this over 80 columns.");
 }
+>>> Empty method bodies may be on a single line (or more)
+void main() { }
+<<<
+void main() {}
+>>>
+void main() {
+
+}
+<<<
+void main() {
+
+}