Check for class expressions in inspectDeclarator

[MartijnWelker]

Currently inspectDeclarator only checks for (arrow)function expressions, but it should also check for class expressions in the form of:

/*@ngInject*/
let MyClass = class MyClass { // or as unnamed class
  constructor (myService) {
  }
};

and

let MyClass = class MyClass { // or as unnamed class

  /*@ngInject*/
  constructor (myService) {
  }
};

If you enter the above code in the testpage WITHOUT compiling to ES5 the injection tokens won't be added.

[timofei-iatsenko]

Damned, I did the same https://github.com/schmod/babel-plugin-angularjs-annotate/pull/55 but also added a test case

[MartijnWelker]

Closing in favour of #55