SuperCall incorrectly tolerated outside of class constructors

[jugglinmike]

As of version 2.12.0, JSHint incorrectly allows SuperCall expression to appear in class methods.

For example, the following text contains 3 syntax errors, but JSHint does not recognize any of them:

/* jshint esversion: 6 */
class C {
  method() {
    super();
  }
  static staticMethod() {
    super();
  }
  *generatorMethod() {
    super();
    yield;
  }
}