ART: Revert change to LiveRange::Dump

Changes back the LiveRange printing format to "[start,end)" for better
clarity. However, it removes the space after comma due to b/1189305
and prints the "ranges" attribute with curly brackets to improve
readability.

Bug: 21189305
Change-Id: Ic83025fa78d6f1edb5e0e39d66160182b0198ab8