Turn LoadIndexedInterceptor into a Turbofan stub

src/compiler/code-stub-assembler.h

Index: src/compiler/code-stub-assembler.h
diff --git a/src/compiler/code-stub-assembler.h b/src/compiler/code-stub-assembler.h
index 6f0924030337c330103fd3d85be6913308c491ef..40fa82e1593c90ed9141a50ecc4bced51234fba9 100644
--- a/src/compiler/code-stub-assembler.h
+++ b/src/compiler/code-stub-assembler.h
@@ -273,6 +273,9 @@ class CodeStubAssembler {
   // Check a value for smi-ness
   Node* WordIsSmi(Node* a);
 
+  // Check that the value is a positive smi.
+  Node* WordIsPositiveSmi(Node* a);
+
   // Load an object pointer from a buffer that isn't in the heap.
   Node* LoadBufferObject(Node* buffer, int offset,
                          MachineType rep = MachineType::AnyTagged());