Reverts change to debug_lib.dart

Reverts change to debug_lib.dart

Even though this behavior hid failures on ARM and MIPS, it
appears that some test rely on it.

R=regis@google.com

Committed: https://code.google.com/p/dart/source/detail?r=28070

[regis, 2013-09-30 22:09:13]

LGTM

[zra, 2013-09-30 22:11:49]

Committed patchset #1 manually as r28070 (presubmit successful).

[Florian Schneider, 2013-10-01 09:15:30]

On 2013/09/30 22:07:30, zra wrote:

This way we won't get full coverage for the other debugger tests. Wouldn't it be
easier to just mark the test as failing until it is fixed?

[zra, 2013-10-01 14:47:33]

On 2013/10/01 09:15:30, Florian Schneider wrote:
> On 2013/09/30 22:07:30, zra wrote:
> 
> This way we won't get full coverage for the other debugger tests. Wouldn't it
be
> easier to just mark the test as failing until it is fixed?

Since the failure appears to be somewhat timing dependent, and since I am
unfamiliar with the debugger tests, it would be a process of trail-and-error
figuring out which tests to mark as failing. Instead, I have created Issue
13721.