Introduce float32x4.construct and int32x4.construct
Temporarily disable the DebugResultChecksso that the debug version could
give a similar speedup than release version for SIMD benchmarks
Implement int32x4.GetX, GetY, GetZ and GetW, float32x4.withX, withY,
withZ and withW, int32x4.withX, withY, withZ and withW,
int32x4.withFlagX, int32x4.withFlagY, int32x4.withFlagZ and
int32x4.withFlagW
Handle MIRType_Boolean in inlining and type conversion
Implement int32x4.bool, float32x4.clamp and int32x4.select
Implement float32x4 and int32x4's shuffle and shuffleMix