grpc-js: Fix exitIdle propagation and DNS IP result backoff

Author: murgatroid99

packages/grpc-js/src/load-balancer-child-handler.ts

@@ -125,9 +125,9 @@ export class ChildLoadBalancerHandler implements LoadBalancer {
   }
   exitIdle(): void {
     if (this.currentChild) {
-      this.currentChild.resetBackoff();
+      this.currentChild.exitIdle();
       if (this.pendingChild) {
-        this.pendingChild.resetBackoff();
+        this.pendingChild.exitIdle();
       }
     }
   }

packages/grpc-js/src/resolver-dns.ts

@@ -144,6 +144,7 @@ class DnsResolver implements Resolver {
     if (this.ipResult !== null) {
       trace('Returning IP address for target ' + uriToString(this.target));
       setImmediate(() => {
+        this.backoff.reset();
         this.listener.onSuccessfulResolution(
           this.ipResult!,
           null,