Add sourceURL to inline assets

This is a super power! It turns out that if you add this to inline
`script` and `style`, DevTools will associate them with a ghost file and
not just `index`. It’ll also pretty print and give much better line
numbers than if embedded in HTML. Stunning.

Author: csswizardry

_includes/head.html

@@ -35,16 +35,21 @@
   {% if layout.lux %}
     LUX.label = '{{ layout.lux }}';
   {% endif %}
+  //# sourceURL=speedcurve.js
 </script>
 
 <script>
   (function(t,e,n,r){function a(){return e&&e.now?e.now():null}if(!n.version){n._events=[];n._errors=[];n._metadata={};n._urlGroup=null;window.RM=n;n.install=function(e){n._options=e;var a=t.createElement("script");a.async=true;a.crossOrigin="anonymous";a.src=r;var o=t.getElementsByTagName("script")[0];o.parentNode.insertBefore(a,o)};n.identify=function(t,e){n._userId=t;n._identifyOptions=e};n.sendEvent=function(t,e){n._events.push({eventName:t,metadata:e,time:a()})};n.setUrlGroup=function(t){n._urlGroup=t};n.track=function(t,e){n._errors.push({error:t,metadata:e,time:a()})};n.addMetadata=function(t){n._metadata=Object.assign(n._metadata,t)}}})(document,window.performance,window.RM||{},"https://cdn.requestmetrics.com/agent/current/rm.js");
   RM.install({
     token: "j5ss3vj:q7xf9tv"
   });
+  //# sourceURL=request-metrics.js
 </script>
 
-<script>(function(){var dbpr=100;if(Math.random()*100>100-dbpr){var d="dbbRum",w=window,o=document,a=addEventListener,scr=o.createElement("script");scr.async=!0;w[d]=w[d]||[];w[d].push(["presampling",dbpr]);["error","unhandledrejection"].forEach(function(t){a(t,function(e){w[d].push([t,e])});});scr.src="https://cdn.debugbear.com/vUKP1Yu0eg5g.js";o.head.appendChild(scr);}})()</script>
+<script>
+  (function(){var dbpr=100;if(Math.random()*100>100-dbpr){var d="dbbRum",w=window,o=document,a=addEventListener,scr=o.createElement("script");scr.async=!0;w[d]=w[d]||[];w[d].push(["presampling",dbpr]);["error","unhandledrejection"].forEach(function(t){a(t,function(e){w[d].push([t,e])});});scr.src="https://cdn.debugbear.com/vUKP1Yu0eg5g.js";o.head.appendChild(scr);}})()
+  //# sourceURL=debugbear.js
+</script>
 
 <script>performance.mark('cssStart');</script>
 <style>
@@ -55,6 +60,8 @@
     {% include css/components.syntax.css %}
   {% endif %}
 
+  /*# sourceURL=csswizardry.css */
+
 </style>
 <script>
   performance.mark('cssEnd');