Feature summary (what you would like to be able to do and where):
Automatically saves changes to the browser cache as people make edits, and if the submit edit fails, it can use the draft to submit edits again.

Use case(s) (list the steps that you performed to discover that problem, and describe the actual underlying problem which you want to solve. Do not describe only a solution):

When a person with a bad network saves an edit, T289937 may be encountered. The introduction of this function can solve this problem.

Benefits (why should this be implemented?):

This can solve the problem mentioned in T289937.