refactor(workbox-build): remove useWith from Eta template configuration

[rtritto]

This PR refactors the Eta template rendering configuration within workbox-build by removing the useWith: true option.

Using with () { ... } blocks (which useWith relies on) is generally considered bad practice in modern JavaScript due to performance implications, potential scoping issues, and incompatibility with Strict Mode.

To accommodate this change, the service worker template (sw-template.ts) has been updated to explicitly reference injected variables using the default it. object property, ensuring compatibility and cleaner variable resolution during template compilation.

Changes

• packages/workbox-build/src/lib/populate-sw-template.ts: Removed useWith: true from the Eta initialization options.
• packages/workbox-build/src/templates/sw-template.ts: Updated all template variable interpolations (e.g., <%= importScripts %>, <%= use(...) %>) to use the explicit it. prefix (e.g., <%= it.importScripts %>, <%= it.use(...) %>).

Reference

with () {} in JavaScript slows down execution and can cause confusing bugs from https://dev.to/bgub/i-built-a-js-template-engine-3x-faster-than-ejs-lj8

[google-cla]

Thanks for your pull request! It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

View this failed invocation of the CLA check for more information.

For the most up to date status, view the checks section at the bottom of the pull request.

[rtritto]

FYI @jayaddison

[jayaddison]

Thanks @rtritto. Could we enable strict mode for the template evaluation?

[rtritto]

Nice catch, I did the commit

[rtritto]

Removed the commit.

The reason useStrict is not a valid configuration option in modern versions of Eta is that simply removing useWith: true already solves the core issue.

Without useWith: true, Eta no longer wraps the template data in a with(it) { ... } block. Instead, it compiles the template into a standard, clean JavaScript function.

Since modern Node.js and TypeScript project environments (especially those using ES Modules or transpilers) run in Strict > Mode by default, the generated template function will naturally inherit this Strict Mode. This automatically provides the expected performance optimizations and security benefits.

If you absolutely need to explicitly enforce the "use strict"; directive inside the compiled function body, the supported way to do this in Eta is to add it directly at the very top of your template file sw-template.ts:

<% "use strict"; %>
/**
 * Welcome to your Workbox-powered service worker!
 ...

However, in most modern codebases, just removing useWith: true and explicitly referencing variables with it. is the correct and sufficient approach.