Bug 218301

I often create local overrides once I notice that there's something I want to change in a resource.  This often happens far down in the resource, so it's annoying to have to re-find the code that I wanted to change after creating the local override.  It'd be ideal to copy/propagate my current selection/scroll to the new content view shown for the local override so that after hitting the button I can instantly start editing.

# STEPS TO REPRODUCE
1. inspect any page
2. select a text-based resource (i.e. not an image) in the Sources Tab
3. scroll down and place the cursor somewhere near the end of the resource
4. click the Create Local Override navigation item

# EXPECTED
a new local override is created for the selected resource with my cursor/selection being exactly where it was before

# ACTUAL
a new local override is created and the newly shown content view is scrolled to the top