5163f80703
Add structure information to HLoopInformation, and use it to generate prettier
loops when the condition can be generated as an expression.
If it can't, it still falls back to the while(true){if(!cond) break;} pattern.
Only handle for/while/for-in, not do-while yet.
Review URL: https://chromiumcodereview.appspot.com//9863037
git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@6023 260f80e4-7a28-3924-810f-c04153c831b5