[wasm] Initialize the root register for WASM tests.

src/x87/macro-assembler-x87.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_X87_MACRO_ASSEMBLER_X87_H_
 #define V8_X87_MACRO_ASSEMBLER_X87_H_
 
 #include "src/assembler.h"
 #include "src/bailout-reason.h"
 #include "src/frames.h"
@@ skipping 253 matching lines @@
 
   // Push and pop the registers that can hold pointers.
   void PushSafepointRegisters() { pushad(); }
   void PopSafepointRegisters() { popad(); }
   // Store the value in register/immediate src in the safepoint
   // register stack slot for register dst.
   void StoreToSafepointRegisterSlot(Register dst, Register src);
   void StoreToSafepointRegisterSlot(Register dst, Immediate src);
   void LoadFromSafepointRegisterSlot(Register dst, Register src);
 
+  // Nop, because x87 does not have a root register.
+  void InitializeRootRegister() {}
+
   void LoadHeapObject(Register result, Handle<HeapObject> object);
   void CmpHeapObject(Register reg, Handle<HeapObject> object);
   void PushHeapObject(Handle<HeapObject> object);
 
   void LoadObject(Register result, Handle<Object> object) {
     AllowDeferredHandleDereference heap_object_check;
     if (object->IsHeapObject()) {
       LoadHeapObject(result, Handle<HeapObject>::cast(object));
     } else {
       Move(result, Immediate(object));
@@ skipping 700 matching lines @@
   }                                                                       \
   masm->
 #else
 #define ACCESS_MASM(masm) masm->
 #endif
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_X87_MACRO_ASSEMBLER_X87_H_