[turbofan] Add Symbol feedback to Equal/StrictEqual.

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 5b94e3ac6ee817700d32664e5fbdc5b562c9bcb4..8b48df4aa0aac5a8c95bce38de7ad764c783260c 100644
--- a/src/code-stub-assembler.h
+++ b/src/code-stub-assembler.h
@@ -772,6 +772,7 @@ class V8_EXPORT_PRIVATE CodeStubAssembler : public compiler::CodeAssembler {
   Node* IsAccessorPair(Node* object);
   Node* IsHeapNumber(Node* object);
   Node* IsName(Node* object);
+  Node* IsSymbolInstanceType(Node* instance_type);
   Node* IsSymbol(Node* object);
   Node* IsPrivateSymbol(Node* object);
   Node* IsJSValueInstanceType(Node* instance_type);