Remove spawnDomIsolate code

Remove spawnDomIsolate code

This is more or less a straight remove of code.  By disabling print and timers on background isolates in Dartium, we can get rid of the last vestiges of spawnDom*.

R=asiva@google.com

Committed: https://code.google.com/p/dart/source/detail?r=28191

[vsm, 2013-10-01 21:02:31]

https://codereview.chromium.org/25536007/diff/2001/tests/html/html.status
File tests/html/html.status (right):

https://codereview.chromium.org/25536007/diff/2001/tests/html/html.status#new...
tests/html/html.status:34: async_test: Fail # Background timers not implemented.
If this looks good, I will file a bug and mark explicitly here before landing.

https://codereview.chromium.org/25536007/diff/2001/tests/isolate/isolate.status
File tests/isolate/isolate.status (right):

https://codereview.chromium.org/25536007/diff/2001/tests/isolate/isolate.stat...
tests/isolate/isolate.status:96: cross_isolate_message_stream_test: Fail # Issue
13433
Note, these tests failed since I disabled timers on background dartium isolates.
 But, that solution was not correct anyway.  runAsync should map to a microtask
API (see 13433) and not timers as previously.

[siva, 2013-10-03 00:21:16]

lgtm

[vsm, 2013-10-03 03:20:12]

Committed patchset #2 manually as r28191 (presubmit successful).