[TomasVotruba]

Combines two related pieces of work into one branch.

1. NoLongInstanceofChainRule

A single boolean chain built from many instanceof checks is a type dispatch in disguise - past a handful of branches it is slower than a keyed lookup and harder to read.

Custom PHPStan rule (utils/phpstan) that flags any boolean chain (||/&&) with more than 7 instanceof checks, suggesting extraction to a helper method, a match(), or a keyed lookup. Each chain is reported once (inner-most offending sub-chain), independent of PHPStan's post-order visit. Threshold is a single const (MAX_INSTANCEOF_COUNT = 7).

4 existing chains exceed the limit; ignored in phpstan.neon for now, to refactor in follow-ups:

• src/NodeAnalyzer/ExprAnalyzer.php (x2)
• src/NodeTypeResolver/PHPStan/Scope/PHPStanNodeScopeResolver.php
• src/PhpParser/Node/NodeFactory.php

2. bench/scope_expr_dispatch_bench.php

Compares the long instanceof chain in PHPStanNodeScopeResolver against property_exists($node, 'expr'). They are not equivalent: property_exists also matches Assign/AssignOp/AssignRef (handled by the dedicated processAssign branch right below), plus ArrowFunction and Foreach_, so it cannot be swapped in. The shorter form is ~3.7-4x cheaper per call, but moot given the divergence. The bench prints the divergent node set and the CPU ratio.

composer complete-check is green.