[stubs] Port KeyedStoreIC_Megamorphic stub to Turbofan

src/code-stub-assembler.h

Index: src/code-stub-assembler.h
diff --git a/src/code-stub-assembler.h b/src/code-stub-assembler.h
index 36e7801bdd188c082a16e0a29e594835e56a8741..e83121a6424d41dab0a3c1aabf2503767cdefe67 100644
--- a/src/code-stub-assembler.h
+++ b/src/code-stub-assembler.h
@@ -1107,6 +1107,14 @@ class V8_EXPORT_PRIVATE CodeStubAssembler : public compiler::CodeAssembler {
   // TypedArray/ArrayBuffer helpers
   compiler::Node* IsDetachedBuffer(compiler::Node* buffer);
 
+ protected:
+  compiler::Node* ElementOffsetFromIndex(compiler::Node* index,
+                                         ElementsKind kind, ParameterMode mode,
+                                         int base_size = 0);
+
+  void HandleStoreICHandlerCase(const StoreICParameters* p,
+                                compiler::Node* handler, Label* miss);
+
  private:
   friend class CodeStubArguments;
 
@@ -1148,9 +1156,6 @@ class V8_EXPORT_PRIVATE CodeStubAssembler : public compiler::CodeAssembler {
                                    compiler::Node* value,
                                    bool transition_to_field, Label* miss);
 
-  void HandleStoreICHandlerCase(const StoreICParameters* p,
-                                compiler::Node* handler, Label* miss);
-
   compiler::Node* TryToIntptr(compiler::Node* key, Label* miss);
   void EmitFastElementsBoundsCheck(compiler::Node* object,
                                    compiler::Node* elements,
@@ -1167,10 +1172,6 @@ class V8_EXPORT_PRIVATE CodeStubAssembler : public compiler::CodeAssembler {
                                         Label* definitely_no_elements,
                                         Label* possibly_elements);
 
-  compiler::Node* ElementOffsetFromIndex(compiler::Node* index,
-                                         ElementsKind kind, ParameterMode mode,
-                                         int base_size = 0);
-
   compiler::Node* AllocateRawAligned(compiler::Node* size_in_bytes,
                                      AllocationFlags flags,
                                      compiler::Node* top_address,