Fixed E_NOTICE: Undefined property in UnexpectedUseOfThis.php

[algo13]

class C
{
    public function f()
    {
        unset($_GET[0]);
    }
}

PHP Notice: Undefined property: PhpParser\Node\Expr\ArrayDimFetch::$name in src/Analyzer/Pass/Statement/UnexpectedUseOfThis.php on line 186

[ovr]

Thanks, merged to master by cherry-pick with small edit about code style
df9e82e

Please avoid merge commits inside your PR's branches

Thanks