For Float/Double masks, VectorMaskCast between VectorStoreMask and VectorLoadMask prevents VectorStoreMask::Identity from collapsing the pair.

This blocks VectorMaskToLong from folding fromLong(...).toLong(). Integral types are unaffected (no VectorMaskCast in their chain).

Reproduces intermittently under StressIncrementalInlining.

Proposed fix is to make VectorStoreMask::Identity look through VectorMaskCast.

Repro in fastdebug with TestVectorMaskToLongFloatDouble.java

Problem visible after fixing https://bugs.openjdk.org/browse/JDK-8375688, as it can assert first.