[regexp] Port RegExpExecStub to CSA (mostly)

src/arm64/interface-descriptors-arm64.cc

Index: src/arm64/interface-descriptors-arm64.cc
diff --git a/src/arm64/interface-descriptors-arm64.cc b/src/arm64/interface-descriptors-arm64.cc
index 988f7e935d9e1d842a7b3031196a3d62649e24ba..ef51ab4393da554b7eb74e52ec1ce155c58e47a3 100644
--- a/src/arm64/interface-descriptors-arm64.cc
+++ b/src/arm64/interface-descriptors-arm64.cc
@@ -57,6 +57,11 @@ const Register MathPowTaggedDescriptor::exponent() { return x11; }
 
 const Register MathPowIntegerDescriptor::exponent() { return x12; }
 
+const Register RegExpExecDescriptor::StringRegister() { return x0; }
+const Register RegExpExecDescriptor::LastIndexRegister() { return x1; }
+const Register RegExpExecDescriptor::StringStartRegister() { return x2; }
+const Register RegExpExecDescriptor::StringEndRegister() { return x3; }
+const Register RegExpExecDescriptor::CodeRegister() { return x8; }
 
 const Register GrowArrayElementsDescriptor::ObjectRegister() { return x0; }
 const Register GrowArrayElementsDescriptor::KeyRegister() { return x3; }