side_effects=true changes this binding with optional chain

[iccir]

Bug report or Feature request?

Bug report

Version (complete output of terser -V or specific git commit)

5.16.8

Complete CLI command or minify() options used

--compress defaults=false,side_effects=true

terser input

(function(o) {
    console.log((0, o?.f)("PASS"));
})({
    a: "FAIL",
    f(b) {
        return this.a || b;
    },
});

terser output or error
FAIL when side_effects=true, PASS when false. Un-tersified code piped directly into node prints PASS.

Expected result
PASS

[iccir]

maintain_this_binding in common.js needs to handle AST_Chain nodes.