iOS 7.x Safari crash POC

iOS7_Crash.js

var tilesSrc = 'img/gods.png',
    tilesCanvas = null,
    tilesImg = null;

function getCanvasFromImage(image) {
	var canvas = document.createElement('canvas');

	canvas.width = image.naturalWidth;
	canvas.height = image.naturalHeight;

	canvas.getContext('2d').drawImage(image, 0, 0);

	return canvas;
}

window.onload = function() {
    tilesImg = new Image();

    tilesImg.src = tilesSrc;

    tilesImg.onload = function() {
        draw1.disabled = "";
        draw2.disabled = "";

        console.log("Image loaded");

        // "convert" image to canvas (so that texture is in correct format)
        tilesCanvas = getCanvasFromImage(this);
    }
};

function drawTiles(ctx, from, w, h) {
    ctx.clearRect(0, 0, 1024, 768);

    var i = 0,
        j = 0,
        x = 56,
        x2 = 0,
        y = 0;

    for (j = 0; j < 10; j++, y+= 32, x = 56, x2 = 0) {
        for (i = 0; i < 14; i++, x += w, x2 += w) {
            ctx.drawImage(from, x, 233, w, h, x2, y, w, h);
        }
    }
}

function draw(mode) {
    var ctx = myCanvas.getContext('2d');

    draw1.disabled = "disabled";
    draw2.disabled = "disabled";

    if (mode === 1) {
        console.log('drawing using image as source');
        drawTiles(ctx, tilesImg, 64, 32);
    } else {
        console.log('drawing using canvas as source');
        drawTiles(ctx, tilesCanvas, 64, 32);
    }

    // disable buttons
    draw1.disabled = "";
    draw2.disabled = "";
}