[turbofan] Change TruncateFloat32ToUint64 to TryTruncateFloat32ToUint64.

src/mips64/macro-assembler-mips64.h

Index: src/mips64/macro-assembler-mips64.h
diff --git a/src/mips64/macro-assembler-mips64.h b/src/mips64/macro-assembler-mips64.h
index 6381ac16743dda6cfa36e2e22a6d280bfc2441ea..1b66b8aeeb34b812bb145978565529971384e019 100644
--- a/src/mips64/macro-assembler-mips64.h
+++ b/src/mips64/macro-assembler-mips64.h
@@ -843,8 +843,10 @@ class MacroAssembler: public Assembler {
                   Register result = no_reg);
 
   // Convert single to unsigned long.
-  void Trunc_ul_s(FPURegister fd, FPURegister fs, FPURegister scratch);
-  void Trunc_ul_s(FPURegister fd, Register rs, FPURegister scratch);
+  void Trunc_ul_s(FPURegister fd, FPURegister fs, FPURegister scratch,
+                  Register result = no_reg);
+  void Trunc_ul_s(FPURegister fd, Register rs, FPURegister scratch,
+                  Register result = no_reg);
 
   void Trunc_w_d(FPURegister fd, FPURegister fs);
   void Round_w_d(FPURegister fd, FPURegister fs);