Dart2JS evaluation of !e does not match specified semantics

[eernstg]

Dart2JS generated code fails with an AssertionError in the following test:

Language/12_Expressions/27_Unary_Expressions_A02_t03.

The co19 issue #726 indicates that the first check in this file should expect an AssertionError rather than a type error. When omitting this check, the remaining test succeeds as stated. Since '!e' subjects the value of e to boolean conversion, we should get true (since a string and a closure are converted to false), so Expect.isTrue should succeed rather than throwing a TypeError.

[karlklose]

This should be fixed when we update to co19 r793 or later.

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Set owner to @eernstg.
Added Fixed label.