Move WebAXObject.cpp to core/ (WIP)

third_party/WebKit/Source/modules/accessibility/AXARIAGridRow.cpp

Index: third_party/WebKit/Source/modules/accessibility/AXARIAGridRow.cpp
diff --git a/third_party/WebKit/Source/modules/accessibility/AXARIAGridRow.cpp b/third_party/WebKit/Source/modules/accessibility/AXARIAGridRow.cpp
index 75b59061c0613ae40f5e576f87fb96d335c2c542..a63bde50b5e14cd2a4c81bad7c76952166cc5914 100644
--- a/third_party/WebKit/Source/modules/accessibility/AXARIAGridRow.cpp
+++ b/third_party/WebKit/Source/modules/accessibility/AXARIAGridRow.cpp
@@ -52,7 +52,7 @@ bool AXARIAGridRow::IsARIATreeGridRow() const {
   return parent->AriaRoleAttribute() == kTreeGridRole;
 }
 
-void AXARIAGridRow::HeaderObjectsForRow(AXObjectVector& headers) {
+void AXARIAGridRow::HeaderObjectsForRow(AXObjectImplVector& headers) {
   for (const auto& cell : Children()) {
     if (cell->RoleValue() == kRowHeaderRole)
       headers.push_back(cell);