error: shorten some r5js.Error.Type enum names.
test/matchers: remove evaluator from r5js.test.matchers.Throws.
test+platform: re-enable JsInterop error tests.
test/matchers: make r5js.test.matchers.Throws ctor private.
test/matchers: make r5js.test.matchers.ParsesAs ctor private.
test/matchers: make r5js.test.matchers.ScansAs_ generic.
test/matchers: make r5js.test.matchers.HasJsValue_ generic.
test/matchers: make r5js.test.matchers.HasStringValue_ generic.