use wasm to speed up supports

src/geo/base.js

@@ -33,6 +33,7 @@
         return out;
     }
 
+    /** track an array of promises as they all complete */
     async function pwait(promises, tracker) {
         let count = 0;
         if (tracker)
@@ -44,6 +45,13 @@
         await Promise.all(promises);
     }
 
+    /** return a promise that resolves after a given time */
+    function ptimer(time) {
+        return new Promise((resolve, reject) => {
+            setTimeout(resolve, time);
+        });
+    }
+
     function numOrDefault(num, def) {
         return num !== undefined ? num : def;
     }
@@ -504,6 +512,7 @@
         round,
         area2,
         pwait,
+        ptimer,
         center2d,
         center2pr,
         thetaDiff,