getting a webgl context fails on macOS about wasmbrowsertest HOT 5 OPEN

> let cc = document.createElement("canvas")
< undefined
> cc.getContext("2d")
< CanvasRenderingContext2D {canvas: canvas, globalAlpha: 1, globalCompositeOperation: 'source-over', filter: 'none', imageSmoothingEnabled: true, …}
> cc.getContext("webgl")
< null

> cat .\examples\test\main_test.go
package main_test

import (
        "syscall/js"
        "testing"
)

func TestWebGL(t *testing.T) {
        window := js.Global().Get("window")
        document := window.Get("document")
        body := document.Get("body")
        canvas := document.Call("createElement", "canvas")
        body.Call("appendChild", canvas)
        if context := canvas.Call("getContext", "webgl"); !context.Truthy() {
                t.Fatal("getContext('webgl') failed")
        }
}

> & (Get-Process -Id $PID).Path { $env:GOOS="js"; $env:GOARCh="wasm"; go test -exec="\\Mac\Home\ebiten\wasmbrowsertest.exe" .\examples\test\ }
--- FAIL: TestWebGL (0.00s)
    main_test.go:18: getContext('webgl') failed
FAIL
exit with status 1
FAIL    github.com/hajimehoshi/ebiten/v2/examples/test  1.130s
FAIL