[stubs] Refactor StringCompareStub and use it for HStringCompareAndBranch.

src/interface-descriptors.h

Index: src/interface-descriptors.h
diff --git a/src/interface-descriptors.h b/src/interface-descriptors.h
index 06e586e876e345cb62884067e33e91f979776f47..6866a97d1e6ecb73b99cfa494be8d243b80eaf4a 100644
--- a/src/interface-descriptors.h
+++ b/src/interface-descriptors.h
@@ -52,6 +52,7 @@ class PlatformInterfaceDescriptor;
   V(BinaryOp)                                 \
   V(BinaryOpWithAllocationSite)               \
   V(StringAdd)                                \
+  V(StringCompare)                            \
   V(Keyed)                                    \
   V(Named)                                    \
   V(CallHandler)                              \
@@ -570,6 +571,16 @@ class StringAddDescriptor : public CallInterfaceDescriptor {
 };
 
 
+class StringCompareDescriptor : public CallInterfaceDescriptor {
+ public:
+  DECLARE_DESCRIPTOR(StringCompareDescriptor, CallInterfaceDescriptor)
+
+  enum ParameterIndices { kLeftIndex, kRightIndex, kParameterCount };
+  static const Register LeftRegister();
+  static const Register RightRegister();
+};
+
+
 class KeyedDescriptor : public CallInterfaceDescriptor {
  public:
   DECLARE_DESCRIPTOR(KeyedDescriptor, CallInterfaceDescriptor)