Add full TurboFan support for accessing SeqString contents.

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 c4b5e0c2cd9a84e78cfb8164411222b4206233b2..d4d1e477e3b2643bf5ef679e16f7eb0368dff6dd 100644
--- a/src/compiler/js-intrinsic-lowering.h
+++ b/src/compiler/js-intrinsic-lowering.h
@@ -40,6 +40,8 @@ class JSIntrinsicLowering FINAL : public Reducer {
   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);