It seems that in https://github.com/WebKit/WebKit/commit/58c68bcae31b110160f93fe60e42387dbf6009ae was done some refactoring things and during that the implementation for the ARM-NEON was removed. Specifically calling function:
platformArithmeticNeon in FEComposite::platformArithmeticSoftware. The functionality from the FEComposite::platformArithmeticSoftware was moved to FECompositeSoftwareApplier::applyArithmetic but without distinguished  separate functionality for HAVE(ARM_NEON_INTRINSICS) and not HAVE(ARM_NEON_INTRINSICS).

There were future fixes for case not HAVE(ARM_NEON_INTRINSICS) (Build error in ARMv7 Neon targets: https://github.com/WebKit/WebKit/commit/a318e830f46865c9f1fdea4e8cd1132891210b08) but there is still missing calling functionality for HAVE(ARM_NEON_INTRINSICS).

The problem was observed and reported for WPE 2.38: https://github.com/WebPlatformForEmbedded/WPEWebKit/issues/1145 as a regression in case of some tests of SVG lightning filters. There is also fix for that: https://github.com/WebPlatformForEmbedded/WPEWebKit/pull/1199 which can be reused in upstream to fix that (SVG lightning filters for ARM-NEON platforms).