R1:7c49f2bf4ffb

Separate loading inline comments from drawing inline comments

Summary:
Currently, we issue one Ajax request to get inline comments, and then draw them when they come back. This has some limitations:

- A user could quickly click image 1, and then click image 2. The request for image 1 may take longer to come back than image 2. In this case, we'd draw the image 2 inlines and then draw the image 1 inlines when that request arrived, resulting in image 2 shown with both image 1 and image 2 comments. This is…