[turbofan] Implemented the optional Float32RoundTruncate operator.

src/compiler/arm64/code-generator-arm64.cc

Index: src/compiler/arm64/code-generator-arm64.cc
diff --git a/src/compiler/arm64/code-generator-arm64.cc b/src/compiler/arm64/code-generator-arm64.cc
index 3107ed0db505010bb5125778b94cc3ca2e07acb1..f8c72575ff9ef76d1e47ef11ac7b2dfd4af67e56 100644
--- a/src/compiler/arm64/code-generator-arm64.cc
+++ b/src/compiler/arm64/code-generator-arm64.cc
@@ -638,6 +638,9 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
     case kArm64Float64RoundTiesAway:
       __ Frinta(i.OutputDoubleRegister(), i.InputDoubleRegister(0));
       break;
+    case kArm64Float32RoundTruncate:
+      __ Frintz(i.OutputFloat32Register(), i.InputFloat32Register(0));
+      break;
     case kArm64Float64RoundTruncate:
       __ Frintz(i.OutputDoubleRegister(), i.InputDoubleRegister(0));
       break;