add tilt field to chart

go/jsruntime/basic.ts

@@ -53,4 +53,8 @@ export function numberToStringWithCommas(n: number):string {
     }
 
     return result;
+}
+
+export function clamp(val: number, min: number, max: number) : number {
+    return Math.min(Math.max(val, min), max);
 }