Keyboard shortcut in chrome for selecting bookmark in bookmark bar
This is not an exact solution to your question. However it is a good option you might like to try.  

If you enable enhanced dictation in system preferences as in the first image below:



Then if you enable “Enable The Dictation Keyword Phrase” as the example in the following image..



Whether or not you have dictation actively enabled, (and this will work in any application you are in) but in Google Chrome,  simply say the command “Computer Show Numbers“ then you will see something like this:



Calling that  command “Computer Show Numbers“, Will visibly assign a number to every element of the application you are in.  At this point all you need to do is say the command “Computer Click 10” (or whatever number you want clicked) and voila!

If dictation is already actively running, it is not necessary to have to say “Computer…”
Just say the command.  But if dictation is not running, saying the word “Computer” and then the command, Will make your computer start listening to what ever you say after saying “Computer”.  This makes it very easy to dictate commands to your computer if dictation is not actively running