[turbofan] Add the TruncateFloat32ToInt32 operator to turbofan.

src/arm/assembler-arm.cc

Index: src/arm/assembler-arm.cc
diff --git a/src/arm/assembler-arm.cc b/src/arm/assembler-arm.cc
index d2e3231bb8a297e11cbf1af16409a6246eb86aa1..123d8f4105969e0fca745f0fa8b0d4f1393ba08f 100644
--- a/src/arm/assembler-arm.cc
+++ b/src/arm/assembler-arm.cc
@@ -2923,6 +2923,12 @@ void Assembler::vcvt_f64_u32(const DwVfpRegister dst,
 }
 
 
+void Assembler::vcvt_s32_f32(const SwVfpRegister dst, const SwVfpRegister src,
+                             VFPConversionMode mode, const Condition cond) {
+  emit(EncodeVCVT(S32, dst.code(), F32, src.code(), mode, cond));
+}
+
+
 void Assembler::vcvt_s32_f64(const SwVfpRegister dst,
                              const DwVfpRegister src,
                              VFPConversionMode mode,