Avoid creating a 6-element array when pre-processing OPS.transform.

The OPS.transform case in EvaluatorPreprocessor_preprocessCommand() is sometimes hot. E.g. when scrolling through one 120 page document it was hit over 14,000 times.

It currently does |new Float32Array(6)|. This patch replaces that with stack variables, which avoids the GC allocations and churn.