[stubs] Factor CSA::GrowElementsCapacity() out of existing code.

src/builtins/builtins-internal.cc

Index: src/builtins/builtins-internal.cc
diff --git a/src/builtins/builtins-internal.cc b/src/builtins/builtins-internal.cc
index b5858c64927e9849809cad4ff77fe0b3407d7ca7..bec6ff36450223c02fc312f1f51fd7c75bafae7a 100644
--- a/src/builtins/builtins-internal.cc
+++ b/src/builtins/builtins-internal.cc
@@ -108,9 +108,8 @@ void Builtins::Generate_GrowFastDoubleElements(CodeStubAssembler* assembler) {
 
   Label runtime(assembler, CodeStubAssembler::Label::kDeferred);
   Node* elements = assembler->LoadElements(object);
-  elements = assembler->CheckAndGrowElementsCapacity(
-      context, elements, FAST_DOUBLE_ELEMENTS, key, &runtime);
-  assembler->StoreObjectField(object, JSObject::kElementsOffset, elements);
+  elements = assembler->TryGrowElementsCapacity(
+      object, elements, FAST_DOUBLE_ELEMENTS, key, &runtime);
   assembler->Return(elements);
 
   assembler->Bind(&runtime);
@@ -129,9 +128,8 @@ void Builtins::Generate_GrowFastSmiOrObjectElements(
 
   Label runtime(assembler, CodeStubAssembler::Label::kDeferred);
   Node* elements = assembler->LoadElements(object);
-  elements = assembler->CheckAndGrowElementsCapacity(
-      context, elements, FAST_ELEMENTS, key, &runtime);
-  assembler->StoreObjectField(object, JSObject::kElementsOffset, elements);
+  elements = assembler->TryGrowElementsCapacity(object, elements, FAST_ELEMENTS,
+                                                key, &runtime);
   assembler->Return(elements);
 
   assembler->Bind(&runtime);