Config double register number as 1 for X87 Turbofan.

src/mips64/assembler-mips64.h

Index: src/mips64/assembler-mips64.h
diff --git a/src/mips64/assembler-mips64.h b/src/mips64/assembler-mips64.h
index 9aabe1b3164518eaa78be7400b7ae081821d91eb..1d630044b601195ed36fc143a0d4b3a54ea80777 100644
--- a/src/mips64/assembler-mips64.h
+++ b/src/mips64/assembler-mips64.h
@@ -218,6 +218,14 @@ struct FPURegister {
   // TODO(turbofan): Proper support for float32.
   inline static int NumAllocatableAliasedRegisters();
 
+  static int NumAllocatableRegistersForTurbo() {
+    return kMaxNumAllocatableRegisters;
+  }
+
+  static int NumAllocatableAliasedRegistersForTurbo() {
+    return NumAllocatableAliasedRegisters();
+  }
+
   inline static int ToAllocationIndex(FPURegister reg);
   static const char* AllocationIndexToString(int index);