[stubs] Add CSA::IsSymbol() and CSA::IsPrivateSymbol().

src/code-stub-assembler.h

Index: src/code-stub-assembler.h
diff --git a/src/code-stub-assembler.h b/src/code-stub-assembler.h
index f710a499b59e9ae16606ae4912d22398cef590c1..ab878870535a2e83c94e47f55ac5707ea9343a24 100644
--- a/src/code-stub-assembler.h
+++ b/src/code-stub-assembler.h
@@ -639,6 +639,8 @@ class V8_EXPORT_PRIVATE CodeStubAssembler : public compiler::CodeAssembler {
   Node* IsMap(Node* object);
   Node* IsCallableMap(Node* map);
   Node* IsName(Node* object);
+  Node* IsSymbol(Node* object);
+  Node* IsPrivateSymbol(Node* object);
   Node* IsJSValue(Node* object);
   Node* IsJSArray(Node* object);
   Node* IsNativeContext(Node* object);