PHP7 basic support

[yjiq150]

Hi,

I appreciate your spidermonkey extension for PHP. I converted it for PHP7.2 in order to use it on my project with PHP7.x projects.

Currently every other basic functions are working very well on my general tests except the fact that you can't register closures from PHP to JS (It was not common use case for me so I didn't fix it yet).

[Summary]

• Added few more basic test cases for the better test coverage.
• 8 test case successes out of 12 in PHP 7.2
• 6 test case successes out of 12 in PHP 7.1.x (I'm not sure but it seems that there were some issues related to zend_call_function in PHP 7.1.x)
• Rest of the test cases are failing because registerFunction with closure is not currently working (left as todo)
• Creating JS context & running Javascript is working well without memory leaks.

Please let me know if you find any errors or have any suggestions.

Thank you.
YoungJae