BridgeJS: Well-known symbol properties shouldn't be imported

[kateinoigakukun]

Currrently this kind of declaration is generated by ImportTS but it's not a valid Swift code

    var [Symbol.toStringTag]: String {
        get throws(JSException) {
            #if arch(wasm32)
            @_extern(wasm, module: "MyLibrary", name: "bjs_ArrayBuffer_[Symbol.toStringTag]_get")
            func bjs_ArrayBuffer_[Symbol.toStringTag]_get(_ self:Int32)->Int32
            #else
            func bjs_ArrayBuffer_[Symbol.toStringTag]_get(_ self:Int32)->Int32{
                fatalError("Only available on WebAssembly")
            }
            #endif
            let ret = bjs_ArrayBuffer_[Symbol.toStringTag] _get(self.bridgeJSLowerParameter())
            if let error = _swift_js_take_exception() {
                throw error
            }
            return String.bridgeJSLiftReturn(ret)
        }
    }