This is one thing flex and flash are missing. Code formating.
I've tested few eclipse plugins but none of them worked like this one. You can download it from http://sourceforge.net/projects/flexformatter/
Just copy it in your ecplise/plugins folder and restart. You can also import/export your settings in a .properties file
Ctrl-Shift-F is the default shortcut key to format the selected code. Also it's possible to assign another shortcut combination or using the red circled button on the image above.