[turbofan] Remove dead code (related to the SeqStringChar lowering removal).

src/compiler/js-intrinsic-lowering.h

Index: src/compiler/js-intrinsic-lowering.h
diff --git a/src/compiler/js-intrinsic-lowering.h b/src/compiler/js-intrinsic-lowering.h
index 12bd88c83be22693320c495333c57d20909a5279..b0bd007698fec50d8a648d4c00c4e2d2168023da 100644
--- a/src/compiler/js-intrinsic-lowering.h
+++ b/src/compiler/js-intrinsic-lowering.h
@@ -53,8 +53,6 @@ class JSIntrinsicLowering final : public AdvancedReducer {
   Reduction ReduceMathClz32(Node* node);
   Reduction ReduceMathFloor(Node* node);
   Reduction ReduceMathSqrt(Node* node);
-  Reduction ReduceSeqStringGetChar(Node* node, String::Encoding encoding);
-  Reduction ReduceSeqStringSetChar(Node* node, String::Encoding encoding);
   Reduction ReduceStringGetLength(Node* node);
   Reduction ReduceValueOf(Node* node);
   Reduction ReduceFixedArrayGet(Node* node);