fix(elbv2): unable to specify load balancer name

Since #973, the renames of CFN properties from "name" to "xxxName" were
removed. But the ELBv2 library still used `loadBalancerName`. The reason
this was not discovered was because we are splatting `additionalProps` of
type `any`, and this caused the type checker to stop verifying property
names.

Fixes #1481

packages/@aws-cdk/aws-elasticloadbalancingv2/lib/shared/base-load-balancer.ts

@@ -104,7 +104,7 @@ export abstract class BaseLoadBalancer extends cdk.Construct implements route53.
     this.vpc = baseProps.vpc;
 
     const resource = new CfnLoadBalancer(this, 'Resource', {
-      loadBalancerName: baseProps.loadBalancerName,
+      name: baseProps.loadBalancerName,
       subnets: subnets.map(s => s.subnetId),
       scheme: internetFacing ? 'internet-facing' : 'internal',
       loadBalancerAttributes: new cdk.Token(() => renderAttributes(this.attributes)),

packages/@aws-cdk/aws-elasticloadbalancingv2/test/alb/test.load-balancer.ts

@@ -4,6 +4,7 @@ import s3 = require('@aws-cdk/aws-s3');
 import cdk = require('@aws-cdk/cdk');
 import { Test } from 'nodeunit';
 import elbv2 = require('../../lib');
+import { Stack } from '@aws-cdk/cdk';
 
 export = {
   'Trivial construction: internet facing'(test: Test) {
@@ -186,4 +187,22 @@ export = {
 
     test.done();
   },
+
+  'loadBalancerName'(test: Test) {
+    // GIVEN
+    const stack = new Stack();
+    const vpc = new ec2.VpcNetwork(stack, 'Stack');
+
+    // WHEN
+    new elbv2.ApplicationLoadBalancer(stack, 'ALB', {
+      loadBalancerName: 'myLoadBalancer',
+      vpc
+    });
+
+    // THEN
+    expect(stack).to(haveResource('AWS::ElasticLoadBalancingV2::LoadBalancer', {
+      Name: 'myLoadBalancer'
+    }));
+    test.done();
+  },
 };

packages/@aws-cdk/aws-elasticloadbalancingv2/test/nlb/test.load-balancer.ts

@@ -75,4 +75,23 @@ export = {
 
     test.done();
   },
+
+  'loadBalancerName'(test: Test) {
+    // GIVEN
+    const stack = new cdk.Stack();
+    const vpc = new ec2.VpcNetwork(stack, 'Stack');
+
+    // WHEN
+    new elbv2.NetworkLoadBalancer(stack, 'ALB', {
+      loadBalancerName: 'myLoadBalancer',
+      vpc
+    });
+
+    // THEN
+    expect(stack).to(haveResource('AWS::ElasticLoadBalancingV2::LoadBalancer', {
+      Name: 'myLoadBalancer'
+    }));
+    test.done();
+  }
+
 };