Performance: Avoid extra calls to realpath

[aristath]

The register_block_style_handle function sets a variable with this code: $wpinc_path_norm = wp_normalize_path( realpath( ABSPATH . WPINC ) );
That value never changes, so we can convert that var to be a static variable. By doing so, we can avoid ~200 calls to realpath and wp_normalize_path (more if 3rd-party plugins register styles)

Trac ticket: https://core.trac.wordpress.org/ticket/56758

[mukesh27]

@aristath PR look good. I left a comment.

[SergeyBiryukov]

In 54415:

Blocks: Avoid extra calls to realpath() in block scripts and styles registration.

This affects:

• register_block_script_handle()
• register_block_style_handle()

Both functions set a variable with this code:

$wpinc_path_norm = wp_normalize_path( realpath( ABSPATH . WPINC ) );

That value never changes during page load, so we can save it to a static variable. By doing so, we can avoid ~200 calls to realpath() and wp_normalize_path(), or even more if third-party plugins register scripts or styles.

Follow-up to [52291], [52939], [54290], [54291], [54309], [54327].

Props aristath, mukesh27, SergeyBiryukov.
Fixes #56758.

Thanks for the PR! Merged in r54415.