[stubs] Refactor StringCompareStub and use it for HStringCompareAndBranch.

src/arm/interface-descriptors-arm.cc

Index: src/arm/interface-descriptors-arm.cc
diff --git a/src/arm/interface-descriptors-arm.cc b/src/arm/interface-descriptors-arm.cc
index 09fdd5bada4ee6766e09a82293da8bdb2adff930..52084fd3dcff8d30be18c0eb0697353e086a225f 100644
--- a/src/arm/interface-descriptors-arm.cc
+++ b/src/arm/interface-descriptors-arm.cc
@@ -52,6 +52,10 @@ const Register InstanceOfDescriptor::LeftRegister() { return r1; }
 const Register InstanceOfDescriptor::RightRegister() { return r0; }
 
 
+const Register StringCompareDescriptor::LeftRegister() { return r1; }
+const Register StringCompareDescriptor::RightRegister() { return r0; }
+
+
 const Register ArgumentsAccessReadDescriptor::index() { return r1; }
 const Register ArgumentsAccessReadDescriptor::parameter_count() { return r0; }