[compiler] Introduce StringEqualStub and StringNotEqualStub.

src/compiler/code-stub-assembler.h

Index: src/compiler/code-stub-assembler.h
diff --git a/src/compiler/code-stub-assembler.h b/src/compiler/code-stub-assembler.h
index 0edf7a55c912829bfb567973f979bd7dd5ce2552..04bc05c5c17a770c0f456827e5450378353d2bcc 100644
--- a/src/compiler/code-stub-assembler.h
+++ b/src/compiler/code-stub-assembler.h
@@ -19,6 +19,7 @@
 namespace v8 {
 namespace internal {
 
+class Callable;
 class CallInterfaceDescriptor;
 class Isolate;
 class Factory;
@@ -215,6 +216,9 @@ class CodeStubAssembler {
                  Node* context, Node* arg1, Node* arg2, Node* arg3, Node* arg4,
                  Node* arg5, size_t result_size = 1);
 
+  Node* TailCallStub(Callable const& callable, Node* context, Node* arg1,
+                     Node* arg2, size_t result_size = 1);
+
   Node* TailCallStub(const CallInterfaceDescriptor& descriptor, Node* target,
                      Node* context, Node* arg1, Node* arg2,
                      size_t result_size = 1);