… holders

For property fetches and array dim fetches, the target type in conditional
expression holders must be computed from the right-side scope where the base
object is already narrowed. For example, `$node->name` needs `$node` narrowed
to `FuncCall` (not `CallLike`) to resolve the property type correctly.

Variables keep using the original scope to avoid breaking multi-var isset()
where the right scope has already removed null from the other variable.

Also removes a redundant `!($expr->name instanceof Name)` check that PHPStan
correctly identified as always-true after the preceding elseif branch.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>