Much of this change can be done using automated scripts.

This handles only the cases that are 'straightforward', ie. where the output of Promise.defer() is assigned to a local variable that isn't re-used for something else. Restricting to this specific (most common) case lets the script completely remove the variable.

This is the script I used to generate attachment 8865256 [details] [diff] [review].

https://treeherder.mozilla.org/#/jobs?repo=try&revision=b08453ff9df93104919bc32adc98af81d2e08b8b looks pretty green.

Comment on attachment 8865256 [details] [diff] [review] script-generated patch Review of attachment 8865256 [details] [diff] [review]: ----------------------------------------------------------------- Can I get a diff -w for this patch?

Sure, the diff -w has 725 changed lines instead of 2721 in the full diff.

Pushed by florian@queze.net: https://hg.mozilla.org/mozilla-central/rev/c143205c3f20 script-generated patch to switch from Promise.defer() to new Promise() where it's straightforward, rs=Mossop. https://hg.mozilla.org/mozilla-central/rev/78bda617988b hand cleanup after applying the previous script-generated patch, r=Mossop.

https://hg.mozilla.org/mozilla-central/rev/c143205c3f20 https://hg.mozilla.org/mozilla-central/rev/78bda617988b