Token.toNumber fails with Tcp/UdpPort after the ...FromAttribute versions were removed

[brad-jones]

Describe the bug
After this was merged #2580 I now see errors like this:

(node:22) UnhandledPromiseRejectionWarning: Error: Token value is not number or lazy, can't represent as number: ${Token[DBCluster.Endpoint.Port.199]}
    at Token.toNumber (/app/node_modules/.registry.npmjs.org/@aws-cdk/cdk/0.32.0/node_modules/@aws-cdk/cdk/lib/token.ts:162:15)
    at new PostgreSQLDb (/app/context/nbnsq-infra/constructs/PostgreSQLDb.ts:92:52)
    at new NbnSq (/app/context/nbnsq-infra/stacks/NbnSq.ts:354:17)
    at /app/context/nbnsq-infra/app.ts:137:2

To Reproduce

const sg = new SecurityGroup(this, "SecurityGroup", {...});
const cluster = new CfnDBCluster(this, "DBCluster", {...});
sg.addIngressRule(
    new CidrIPv4('127.0.0.1/32'),
    new TcpPort(new Token(cluster.dbClusterEndpointPort).toNumber())
);

Expected behavior
TcpPort to accept the Token after being converted with toNumber as outlined in the v0.32.0 change log: "ec2.TcpPortFromAttribute and UdpPortFromAttribute removed. Use TcpPort and UdpPort with new Token(x).toNumber instead."

Work around
This still produces a working template.

const sg = new SecurityGroup(this, "SecurityGroup", {...});
const cluster = new CfnDBCluster(this, "DBCluster", {...});
sg.addIngressRule(
    new CidrIPv4('127.0.0.1/32'),
    cluster.dbClusterEndpointPort as any as number
);

Version:

• Programming Language: Typescript
• CDK Version: 0.32.0