In the Review Request screen, clicking Update -> Add File would not do

anything.
The Update element's click event is registered before the Add File

element's click event. As a result, the Update element's click event is

firing before, eating up the Add File's click event and thus causing the

upload file dialog to never appear.
The onUploadFileClicked() function was moved from ReviewablePageView to

ReviewRequestEditorView, and the element's handler registered in the

setupActions() function. The .has-menu handler was moved to

ReviewablePageView, better respecting the ownership structure of the

page. This changes the order in which the click events are fired, allowing

the onUploadFileClicked() function to actually fire in response to the

Add File element being clicked.
Furthermore, the has-menu handler was moved from 

ReviewRequestEditorView to ReviewablePageView 
After the fix, the upload file dialog appears as intended.

Ran JSTests.
Tested manually by clicking Update -> Add File, where the upload file

dialog appears. This was done on both computer and mobile browsers.