This speeds up remove_possible_method substantially since it doesn't
have to rescue a NameError in the common case.

Closes #2346.

This reverts commit 6f29b356.

Reason: Changelogs are not meant to be changed in docrails.

American English(according to Weber)

Port from 3-1-stable

Came with this one-liner for this:

    find . -name '*.rb' | \
    xargs chardet | \
    grep -v ascii | \
    cut -d: -f1 -s | \
    xargs -n1 ruby -0777 -ne 'puts $FILENAME if $_ !~ /#.*coding:\s*utf/i'

Welcome $_.

Changed the year of a date used in a test which fails when using 1.8.7 on a 32bit machine (ArgumentError: time out of range)

Don't do remove_possible_method when delegate is used. Two reasons: 1) warnings should be shown, and fixed at the source and 2) the code is slow. Fixes #1937.

Current implementation produce incorrect output when Time#usec returns
integer < 100000, because to_s doesn't add leading zeros.