[turbofan] Eliminate redundant CheckString based on types.

src/compiler/js-typed-lowering.h

Index: src/compiler/js-typed-lowering.h
diff --git a/src/compiler/js-typed-lowering.h b/src/compiler/js-typed-lowering.h
index b1f4165c9ad2cc1a41a70e63726185219863cdb0..cf6a5727edbd4159e75e0f1803356af1ca19c818 100644
--- a/src/compiler/js-typed-lowering.h
+++ b/src/compiler/js-typed-lowering.h
@@ -78,6 +78,7 @@ class JSTypedLowering final : public AdvancedReducer {
   Reduction ReduceJSGeneratorStore(Node* node);
   Reduction ReduceJSGeneratorRestoreContinuation(Node* node);
   Reduction ReduceJSGeneratorRestoreRegister(Node* node);
+  Reduction ReduceCheckString(Node* node);
   Reduction ReduceNumberRoundop(Node* node);
   Reduction ReduceSelect(Node* node);
   Reduction ReduceJSSubtract(Node* node);