Improve search experience in diff screen.
Ctrl-F, Ctrl-G and Shift-Ctrl-G now bind to the search dialog box provided by CodeMirror's search add-on. Enter and Shift-Enter navigate among the search results from the CodeMirror search, just like they do in a normal browser search. Esc now clears the search result.
If the user sets
Slow in the diff preferences and the file is less than 4000 lines (huge), then Ctrl-F, Ctrl-G and Shift-Ctrl-G fall back to the browser search.