Add an exhaustive test of for loops.

Add an exhaustive test of for loops.

Test 52 different versions of for loops created by including or leaving
off various bits of the loop structure.

BUG=
R=iposva@google.com, srdjan@google.com

Committed: https://code.google.com/p/dart/source/detail?r=24384

[Kevin Millikin (Google), 2013-06-21 12:34:42]

All tests pass.  Tests number 26, 27, 56, 57, 58, and 59 would have failed
before the fix to the recent for-loop bug.

[srdjan, 2013-06-21 16:24:15]

LGTM and thanks!

[srdjan, 2013-06-21 16:26:03]

You could make sure that they are run in optimized code as well, by adding a
loop over body of main

[Ivan Posva, 2013-06-21 16:51:23]

LGTM

Thanks,
-Ivan

[Kevin Millikin (Google), 2013-06-25 07:50:52]

Committed patchset #1 manually as r24384 (presubmit successful).