beforeUnload throws exception in Opera

[gramster]

In my main() I have this code:

    window.on.beforeUnload.add(_beforeUnload);

In Opera (11.62)I get this:

Uncaught exception: Error
Error thrown at line 12, column 2 in $throw(e) in file://localhost/home/gram/dart/test/test.dart.js:
    throw e;
called from line 306, column 10 in <anonymous function: method>() in file://localhost/home/gram/dart/test/test.dart.js:
    $throw(new NoSuchMethodException(
called via Function.prototype.apply() from line 317, column 4 in $dynamicBind() in file://localhost/home/gram/dart/test/test.dart.js:
    return method.apply(this, Array.prototype.slice.call(arguments));
called from line 4183, column 2 in Episodes(_includePerfMarks, _autorun) in file://localhost/home/gram/dart/test/test.dart.js:
    get$$window().get$on().get$beforeUnload().add($wrap_call$1(this.get$_beforeUnload()), false);

[anders-sandholm]

Added Area-Frog, Triaged labels.

[anders-sandholm]

Removed Area-Frog label.
Added Area-Dart2JS, OldAreaFrog labels.

[anders-sandholm]

Removed OldAreaFrog label.
Added FromAreaFrog label.

[kasperl]

Removed Area-Dart2JS, FromAreaFrog labels.
Added Area-DOM label.

[vsmenon]

Probably also related to issue #2397.

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Added this to the M1 milestone.

[vsmenon]

Marked this as being blocked by #4111.

[iposva-google]

Removed Area-DOM label.
Added Area-HTML label.

[vsmenon]

Removed this from the M1 milestone.
Added this to the M2 milestone.

[blois]

Removed this from the M2 milestone.
Added this to the Later milestone.

[efortuna]

Added Fixed label.