Fix TSLint rules

packages/contract-wrappers/test/global_hooks.ts

@@ -8,7 +8,8 @@ import { provider } from './utils/web3_wrapper';
 before('migrate contracts', async function(): Promise<void> {
     // HACK: Since the migrations take longer then our global mocha timeout limit
     // we manually increase it for this before hook.
-    this.timeout(20000);
+    const mochaTestTimeoutMs = 20000;
+    this.timeout(mochaTestTimeoutMs);
     const txDefaults = {
         gas: devConstants.GAS_ESTIMATE,
         from: devConstants.TESTRPC_FIRST_ADDRESS,