fix(es/minifier): Add WeakRef as a safe global reference

[lukeapage]

Description:

I was trying to remove references to Weak Ref from minified code and despite the expression not being used, it was still included.

E.g.

var x = WeakRef;

with

{
   "minify": true,
  "jsc": {
      "minify": {
            "compress": {
                "pure_getters": true,
                "unused": true
            },
            "mangle": true
        }
    }
}

outputs

WeakRef;

but when I use something on this list e.g. parseFloat, it gets cleaned up and outputs empty string.

btw - I tried different options for pure_getters that I assumed would allow me to say WeakRef as a getter was pure, but it had no effect.

WeakRef getter is as safe to remove as the other items on this list and has no effect in accessing it.

[CLAassistant]

All committers have signed the CLA.

[kdy1]

Thank you!

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swc-bump:

• swc_ecma_usage_analyzer