Avoiding Unnecessary Paints: Animated GIF Edition
http://www.html5rocks.com/en/tutorials/speed/animated-gifs/
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update translation
remove original sentence.
update link to the Japanese version
add Japanese title and description for the AnimGIF article
Merge pull request #1238 from html5j-english/animgifs-ja

add Japanese translation of "Avoiding Unnecessary Paints: Animated GIF Edition"