Revert of [turbofan] Speculatively optimize string character access.

src/builtins/builtins-string-gen.cc

Index: src/builtins/builtins-string-gen.cc
diff --git a/src/builtins/builtins-string-gen.cc b/src/builtins/builtins-string-gen.cc
index f30111a802d8ca93a81cbb67b6fdb0b2001bc68e..d0f707bcec42ed5b3810e664c6887a8eb0a33a8e 100644
--- a/src/builtins/builtins-string-gen.cc
+++ b/src/builtins/builtins-string-gen.cc
@@ -656,13 +656,7 @@
            &if_positioninbounds);
 
     BIND(&return_emptystring);
-    {
-      // Invalidate the "String Bounds Check" protector.
-      Node* invalid = SmiConstant(Isolate::kProtectorInvalid);
-      Node* cell = LoadRoot(Heap::kStringBoundsCheckProtectorRootIndex);
-      StoreObjectFieldNoWriteBarrier(cell, Cell::kValueOffset, invalid);
-      Return(EmptyStringConstant());
-    }
+    Return(EmptyStringConstant());
 
     BIND(&if_positioninbounds);
   }
@@ -701,13 +695,7 @@
            &if_positioninbounds);
 
     BIND(&return_nan);
-    {
-      // Invalidate the "String Bounds Check" protector.
-      Node* invalid = SmiConstant(Isolate::kProtectorInvalid);
-      Node* cell = LoadRoot(Heap::kStringBoundsCheckProtectorRootIndex);
-      StoreObjectFieldNoWriteBarrier(cell, Cell::kValueOffset, invalid);
-      Return(NaNConstant());
-    }
+    Return(NaNConstant());
 
     BIND(&if_positioninbounds);
   }