Use a register spec for StoreIC and KeyedStoreIC.

src/x64/debug-x64.cc

Index: src/x64/debug-x64.cc
diff --git a/src/x64/debug-x64.cc b/src/x64/debug-x64.cc
index 1870384a5294bc1a04a3c396e712742d375b782b..f00a4efb78b008e0ad1f195cc7d3388cbe850b61 100644
--- a/src/x64/debug-x64.cc
+++ b/src/x64/debug-x64.cc
@@ -170,13 +170,11 @@ void DebugCodegen::GenerateLoadICDebugBreak(MacroAssembler* masm) {
 
 void DebugCodegen::GenerateStoreICDebugBreak(MacroAssembler* masm) {
   // Register state for IC store call (from ic-x64.cc).
-  // ----------- S t a t e -------------
-  //  -- rax    : value
-  //  -- rcx    : name
-  //  -- rdx    : receiver
-  // -----------------------------------
+  Register receiver = StoreIC::ReceiverRegister();
+  Register name = StoreIC::NameRegister();
+  Register value = StoreIC::ValueRegister();
   Generate_DebugBreakCallHelper(
-      masm, rax.bit() | rcx.bit() | rdx.bit(), 0, false);
+      masm, receiver.bit() | name.bit() | value.bit(), 0, false);
 }
 
 
@@ -187,14 +185,12 @@ void DebugCodegen::GenerateKeyedLoadICDebugBreak(MacroAssembler* masm) {
 
 
 void DebugCodegen::GenerateKeyedStoreICDebugBreak(MacroAssembler* masm) {
-  // Register state for keyed IC load call (from ic-x64.cc).
-  // ----------- S t a t e -------------
-  //  -- rax    : value
-  //  -- rcx    : key
-  //  -- rdx    : receiver
-  // -----------------------------------
+  // Register state for keyed IC store call (from ic-x64.cc).
+  Register receiver = KeyedStoreIC::ReceiverRegister();
+  Register name = KeyedStoreIC::NameRegister();
+  Register value = KeyedStoreIC::ValueRegister();
   Generate_DebugBreakCallHelper(
-      masm, rax.bit() | rcx.bit() | rdx.bit(), 0, false);
+      masm, receiver.bit() | name.bit() | value.bit(), 0, false);
 }