Fix source-less JS handle ordering

[luismulinari]

Description

• Defers source-less JS handles through the same ordered output queue used for non-concatenated scripts.
• Keeps pending concat chunks before alias/group inline output, matching WordPress' WP_Scripts::do_item() ordering behavior.
• Adds a regression test covering js_do_concat disabled with a source-less handle that has script dependencies and inline output.

[Copilot]

Pull request overview

This PR adjusts WPcom_JS_Concat::do_items() so that source-less (alias/group) script handles are deferred into the same ordered output queue as non-concatenated scripts, ensuring concatenated chunks are emitted before any inline output attached to those source-less handles (aligning more closely with WordPress core ordering).

Changes:

• Defer source-less script handles by queueing them as do_item entries instead of printing immediately.
• Add a regression test to validate ordering when js_do_concat is disabled and a source-less handle has dependencies plus inline output.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
jsconcat.php	Defers source-less handles into the ordered $javascripts queue so pending concat chunks print before alias/group inline output.
tests/test-jsconcat-order.php	Adds a regression test that asserts output ordering for a source-less handle when concat is disabled.

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