Modify dart:isolate tests to run on Dartium

[vsmenon]

We no longer support spawnFunction from the DOM isolate on Dartium. Instead, spawnUri must be used to create a background isolate (which cannot access dart:html). spawnFunction may be used from background isolates.

The following tests now fail on Dartium. We should consider either:
(a) Modifying the tests to use spawnUri
(b) Running them automatically in a background isolate (in the test framework?)

browser/compute_this_script_browser_stream_test: Fail
browser/compute_this_script_browser_test: Fail
count_stream_test: Fail
count_test: Fail
cross_isolate_message_test: Fail
global_error_handler2_test: Fail
global_error_handler_stream2_test: Fail
global_error_handler_stream_test: Fail
global_error_handler_test: Fail
illegal_msg_stream_test: Fail
illegal_msg_test: Fail
isolate_complex_messages_stream_test: Fail
isolate_complex_messages_test: Fail
mandel_isolate_stream_test: Fail
mandel_isolate_test: Fail
message2_test: Fail
message_stream2_test: Fail
message_stream_test: Fail
message_test: Fail
mint_maker_test: Fail
nested_spawn2_test: Fail
nested_spawn_stream_test: Fail
nested_spawn_test: Fail
request_reply_test: Fail
spawn_function_custom_class_test: Fail
spawn_function_test: Fail
stacktrace_message_test: Fail
unresolved_ports_test: Fail

[vsmenon]

Actually, this breaks many more tests in the unittest package and elsewhere. See:

https://codereview.chromium.org/26616002/

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cc @ricowind.

[ricowind]

Special casing the running of certain tests in the test controller because the tests are wrongly written seems like a bad idea to me. Is anything preventing us from simply fixing up the tests?

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cc @mkustermann.

[ricowind]

So Florian actually have a cl pending:
https://codereview.chromium.org/20703003/
Where he fixes up the isolate spawn functionality so that the tests can catch these spawnFunction errors and report something reasonable (we sort of already can, we can pass in a error callback)
I added a comment here:
https://codereview.chromium.org/26397003/
asking why we don't throw an exception instead of reporting a problem (which will go to the console).
I think we need to figure that out
Assigning back to Vijay to get input on this

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Set owner to @vsmenon.
Added NeedsInfo label.

[lrhn]

Added Library-Isolate label.

[lrhn]

Issue #14626 has been merged into this issue.

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cc @vsmenon.

[lrhn]

Marked this as being blocked by #17649.