[regexp] Port RegExpExecStub to CSA (mostly)

src/x87/interface-descriptors-x87.cc

Index: src/x87/interface-descriptors-x87.cc
diff --git a/src/x87/interface-descriptors-x87.cc b/src/x87/interface-descriptors-x87.cc
index 756e2783c44c667d675f7788e7a2a5f2c7e92a38..ef03302c19dfb280619a1b41b4d345c4cac2338a 100644
--- a/src/x87/interface-descriptors-x87.cc
+++ b/src/x87/interface-descriptors-x87.cc
@@ -52,11 +52,15 @@ const Register ApiGetterDescriptor::CallbackRegister() { return eax; }
 
 const Register MathPowTaggedDescriptor::exponent() { return eax; }
 
-
 const Register MathPowIntegerDescriptor::exponent() {
   return MathPowTaggedDescriptor::exponent();
 }
 
+const Register RegExpExecDescriptor::StringRegister() { return eax; }
+const Register RegExpExecDescriptor::LastIndexRegister() { return ecx; }
+const Register RegExpExecDescriptor::StringStartRegister() { return edx; }
+const Register RegExpExecDescriptor::StringEndRegister() { return ebx; }
+const Register RegExpExecDescriptor::CodeRegister() { return edi; }
 
 const Register GrowArrayElementsDescriptor::ObjectRegister() { return eax; }
 const Register GrowArrayElementsDescriptor::KeyRegister() { return ebx; }