Fix nikic#718: PrettyPrinter breaks nested ternaries

Mark ternary as non-associative operator, as left-associative use
is deprecated in PHP 7.4 and removed in PHP 8.0.

Author: nikic

lib/PhpParser/PrettyPrinterAbstract.php

@@ -66,7 +66,7 @@ abstract class PrettyPrinterAbstract
         BinaryOp\BooleanAnd::class     => [120, -1],
         BinaryOp\BooleanOr::class      => [130, -1],
         BinaryOp\Coalesce::class       => [140,  1],
-        Expr\Ternary::class            => [150, -1],
+        Expr\Ternary::class            => [150,  0],
         // parser uses %left for assignments, but they really behave as %right
         Expr\Assign::class             => [160,  1],
         Expr\AssignRef::class          => [160,  1],

test/code/prettyPrinter/expr/parentheses.test

@@ -59,7 +59,7 @@ $a = $b = $c = $d = $f && true;
 ($a = $b = $c = $d = $f) && true;
 $a = $b = $c = $d = $f and true;
 $a = $b = $c = $d = ($f and true);
-$a ? $b : $c ? $d : $e ? $f : $g;
+(($a ? $b : $c) ? $d : $e) ? $f : $g;
 $a ? $b : ($c ? $d : ($e ? $f : $g));
 $a ? $b ? $c : $d : $f;
 $a ?? $b ?? $c;