fix: skip unnecessary network reset during emulation restore

[dhananjay6561]

solves #1797

Summary

Fixes a Lighthouse audit failure where Network.emulateNetworkConditions could hang during emulation restore.

Root cause

lighthouse_audit always runs restoreEmulation() in a finally block.
During restore, McpContext.emulate() always called page.emulateNetworkConditions(null) when networkConditions was not set.
On some Chrome/CDP combinations, that reset call can time out even though no network emulation was active.

What changed

• Added an internal skipNetworkReset option to McpContext.emulate().
• Updated restoreEmulation() to skip the network reset when the page had no saved networkConditions.
• Kept all other emulation restore behavior unchanged.

Validation

• npm run test:no-build -- tests/McpContext.test.ts
• npm run test:no-build -- tests/tools/lighthouse.test.ts

Risk

Low. The change only avoids one unnecessary network-reset call when there was nothing to reset.

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[dhananjay6561]

@Lightning00Blade hi!
kindly review the pr!

[dhananjay6561]

@zyzyzyryxy kindly review!

[zyzyzyryxy]

Hello, thank you for your contribution! As described in the bug report comment, this PR doesn't fully fix the issue, just moves the goalpost. With your change I see timeout on Network.setUserAgentOverride instead of Network.emulateNetworkConditions

[dhananjay6561]

@zyzyzyryxy my prev change avoided the timeout on Network.emulateNetworkConditions, but it still left other restore-time reset calls in place, which is why the failure shifted to Network.setUserAgentOverride.

updated restore logic to skip all unspecified reset calls when there’s nothing to restore, instead of only skipping the network reset. That prevents the timeout from just moving to another CDP command. also added a regression test to verify restore does not call setUserAgent in that no-emulation case.

[zyzyzyryxy]

@dhananjay6561

updated restore logic to skip all unspecified reset calls when there’s nothing to restore [...]

Sorry, I don't see this update, only merges from main. Please double check you did push correctly.

[wolfib]

#1797 has been fixed