The isError_ check uses a heuristic that calls the Function constructor
to determine if the given value is an Error object. This results in a
runtime violation in test suites that enforce Trusted Types.
Since Trusted Types are only supported in modern browsers (currently,
Chromium-based browsers), we can use a more straightforward heuristic in
environments where Trusted Types are supported.
Fixes#1910. See that thread for more details.
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