Tests which characters can be used before a protocol relative URL within an HTML style attribute.
<div id=x style="background:url($[chr]//fuzz.shazzer.co.uk/$[rand]?$[i]#)">test</div>
<div id=x style="background:url(0x09//fuzz.shazzer.co.uk/6l1a0qg1hw8?9#)">test</div>
<div id=x style="background:url(
//fuzz.shazzer.co.uk/zvjai8xb7c?10#)">test</div>
<div id=x style="background:url(0x0C//fuzz.shazzer.co.uk/fhdeoddh36i?12#)">test</div>
<div id=x style="background:url(
//fuzz.shazzer.co.uk/queqgr2un8?13#)">test</div>
<div id=x style="background:url( //fuzz.shazzer.co.uk/ace7nr9xup?32#)">test</div>
<div id=x style="background:url('//fuzz.shazzer.co.uk/m4kmnmosruf?39#)">test</div>
<div id=x style="background:url(///fuzz.shazzer.co.uk/47pxj49jne3?47#)">test</div>
<div id=x style="background:url(\//fuzz.shazzer.co.uk/zg2ndc21amk?92#)">test</div>
<div id=x style="background:url(0x09//fuzz.shazzer.co.uk/2f1m82kh9xz?9#)">test</div>
<div id=x style="background:url(
//fuzz.shazzer.co.uk/ny4a1f2jn7f?10#)">test</div>
<div id=x style="background:url(0x0C//fuzz.shazzer.co.uk/uaik4e1fem?12#)">test</div>
<div id=x style="background:url(
//fuzz.shazzer.co.uk/lby7489loq?13#)">test</div>
<div id=x style="background:url( //fuzz.shazzer.co.uk/61qrysnpqoc?32#)">test</div>
<div id=x style="background:url('//fuzz.shazzer.co.uk/z0j2lssb6rk?39#)">test</div>
<div id=x style="background:url(///fuzz.shazzer.co.uk/d4663ir1405?47#)">test</div>
<div id=x style="background:url(\//fuzz.shazzer.co.uk/5z5ptd2dd7p?92#)">test</div>
<div id=x style="background:url(0x09//fuzz.shazzer.co.uk/jr4auyt6y8?9#)">test</div>
<div id=x style="background:url(
//fuzz.shazzer.co.uk/gbl5uwrn518?10#)">test</div>
<div id=x style="background:url(0x0C//fuzz.shazzer.co.uk/0wv2fo4reaf?12#)">test</div>
<div id=x style="background:url(
//fuzz.shazzer.co.uk/735475ahiet?13#)">test</div>