Use double rather than float

sky/examples/touch-demo.sky

 #!mojo mojo:sky_viewer
 <sky>
 <import src="/sky/framework/debug/shake-to-reload.sky" />
 <style>
 dot {
     position: absolute;
     height: 10px;
     width: 10px;
     background-color: #00FF00;
     border-radius: 5px;
@@ skipping 29 matching lines @@
 void goAway(event) {
   whichDot(event).remove();
 }
 
 void stopDots(event) {
   for (Element e in document.querySelectorAll('dot'))
     e.remove();
 }
 
 void runToTheCenter(event) {
-  float radius = (5 + (95 * event.pressure));
+  double radius = (5 + (95 * event.pressure));
   Element dot = whichDot(event);
   dot.style["transform"] = "translate(${event.x-radius}px,${event.y-radius}px)";
   dot.style["width"] = "${2 * radius}px";
   dot.style["height"] = "${2 * radius}px";
   dot.style["border-radius"] = "${radius}px";
 }
 
 void main() {
   document.addEventListener("pointerdown", moreDots);
   document.addEventListener("pointermove", runToTheCenter);
   document.addEventListener("pointerup", goAway);
   document.addEventListener("pointercancel", stopDots);
 }
 </script>
 </sky>