New ClassInstantiation sniff to WordPress-Extra.

[jrfnl]

New sniff to verify that objects being instantiated comply with some basic rules:

• Always use parenthesis.
• Don't have spaces (or comments) between the class name and the parenthesis.
• Don't assign new by reference (PHP only).

Sniffs both PHP as well as JS code.

Auto-fixes missing parentheses and space between class name and parentheses.

Includes unit tests.

Currently doesn't handle cases of object instantiations where the class name is held in a variable variable.

Fixes #919

[GaryJones]

Looks good. Were you planning to send this upstream?

[JDGrimes]

@jrfnl For the record, is there a particular reason why variable variable class names are not supported?

[jrfnl]

Were you planning to send this upstream?

@GaryJones Potentially this could be pulled upstream at some point, though without the assigning by reference check.

For the record, is there a particular reason why variable variable class names are not supported?

@JDGrimes Yes there is. Variable variables can take a lot of forms and it would take a lot of code to attempt to reliably detect whether the class is instantiated with or without parenthesis in that case. It also would most likely still lead to false positives with the sniff getting confused over whether parentheses are part of the variable variable or for the object instantiation.
See https://github.com/wimg/PHPCompatibility/blob/master/PHPCompatibility/Tests/sniff-examples/variable_variables.php for some examples of what would need to be covered.