function GameOverPanel(canvas, textImgPos, restartImgPos, dimensions) {
        this.canvas = canvas;
        this.canvasCtx = canvas.getContext('2d');
        this.canvasDimensions = dimensions;
        this.textImgPos = textImgPos;
        this.restartImgPos = restartImgPos;
        this.draw();
    }
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    /**
Game over panel.
@param {!HTMLCanvasElement} canvas
@param {Object} textImgPos
@param {Object} restartImgPos
@param {!Object} dimensions Canvas dimensions.
@constructor