Config double register number as 1 for X87 Turbofan.

src/compiler/register-configuration.cc

Index: src/compiler/register-configuration.cc
diff --git a/src/compiler/register-configuration.cc b/src/compiler/register-configuration.cc
index 7257aca02f0f236cc6ab515bb57be85cd387276b..a3d3be1790a6a41ea64fb506f3be4b81d525fd3a 100644
--- a/src/compiler/register-configuration.cc
+++ b/src/compiler/register-configuration.cc
@@ -21,8 +21,13 @@ class ArchDefaultRegisterConfiguration : public RegisterConfiguration {
  public:
   ArchDefaultRegisterConfiguration()
       : RegisterConfiguration(Register::kMaxNumAllocatableRegisters,
+#if V8_TARGET_ARCH_X87
+                              1,
+                              1,
+#else
                               DoubleRegister::kMaxNumAllocatableRegisters,
                               DoubleRegister::NumAllocatableAliasedRegisters(),
+#endif
                               general_register_name_table_,
                               double_register_name_table_) {
     DCHECK_EQ(Register::kMaxNumAllocatableRegisters,