Summary:
@public
ErrorUtils.reportError is intended for reporting handled errors to the
server, like timeouts, which means that we shouldn't shove them in the
developer's face.
Test Plan: add `require('ErrorUtils').reportError(new Error('error'))` and see a useful error message with stack but no redbox. Debugger confirms `reportSoftException` is called but it doesn't do anything yet. `reportFatalError` and throwing exceptions still show redboxes.
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