feat(inferTypes): Support class properties

Previously we did not properly infer params on methods that were located on class properties. This
changes things so that we do. It carefully tries to avoid messing up the existing support of class
type annotations, which are similar to class properties at the AST level, but do not have an
associated node, only a type alias.

Fixes #1043

Author: tmcw

__tests__/__snapshots__/test.js.snap

@@ -2,9 +2,11 @@
  * This function destructures with defaults. It should not
  * have any parameter descriptions.
  */
-function destructure(
-  { phoneNumbers = [], emailAddresses = [], ...params } = {}
-) {}
+function destructure({
+  phoneNumbers = [],
+  emailAddresses = [],
+  ...params
+} = {}) {}
 
 /**
  * Similar, but with an array
@@ -43,6 +45,13 @@ class Sink {
     return 1;
   }
 
+  /**
+   * This uses the class property transform
+   */
+  classprop = (a: number): string => {
+    return 'hi';
+  };
+
   /**
    * This method says hello
    */

__tests__/fixture/es6.input.js

@@ -29,7 +29,10 @@ function findTarget(path: ?Object) {
     // foo.x = TARGET
     path = path.get('expression').get('right');
   } else if (t.isObjectProperty(path)) {
-    // var foo = { x: TARGET };
+    // var foo = { x: TARGET }; object property
+    path = path.get('value');
+  } else if (t.isClassProperty(path) && path.get('value').node) {
+    // var foo = { x = TARGET }; class property
     path = path.get('value');
   }