We currently have a handwritten version of the Ivy directive def for NgClass so
we can switch between Ivy and View Engine behavior. This generated code needs to
be kept up-to-date with what the Ivy compiler generates.
PR 30742 recently changed `classMap` such that it now requires allocation of
host binding slots. This means that the `allocHostVars()` function must be
called in the NgClass directive def to match compiler output, but the
handwritten directive def was not updated. This caused a bug where NgClass
was inappropriately overwriting data for other directives because space was
not allocated for its values.
PR Close#31788
215ef3c5f4