Core refactor for WP Block Parser

[dkarfa]

I found the count() inside a loop condition, but WPCS suggest to use that as this way, assign the return value to a variable and use the variable in the loop condition instead.

[ocean90]

WP Block Parser is part of the ​@wordpress/block-serialization-default-parser package. Please submit any changes at ​https://github.com/WordPress/gutenberg first. Thank you!

From a quick look, your patch will break the loop since the count will never be 0.