Fix some unintended matches outside of '<?php'

[adriaanzon]

This adds the contained argument to some syn match calls, to prevent them from matching outside of a php region. It was mostly unnoticeable, but some examples of bad matches were:

• PHPDoc tags matched outside of a php region
• Blade directives from vim-blade weren't correctly highlighted, they were overridden by the pattern of phpFunction. For some reason, only the indented directives didn't match.

Here's a before and after:

before	after

I tested it out for a while and it didn't seem to have any side effects whatsoever.

[StanAngeloff]

Thanks @adriaanzon! I've reviewed those locally and all seems to be in order.

I appreciate the neat pull request and the nicely formatted commit message :star: