Add nextId to traversal order (#4666)

lib/ui/semantics.dart

@@ -399,6 +399,7 @@ class SemanticsUpdateBuilder extends NativeFieldWrapperClass2 {
     String increasedValue,
     String decreasedValue,
     TextDirection textDirection,
+    int nextNodeId,
     int previousNodeId,
     Float64List transform,
     Int32List children,
@@ -423,6 +424,7 @@ class SemanticsUpdateBuilder extends NativeFieldWrapperClass2 {
                 increasedValue,
                 decreasedValue,
                 textDirection != null ? textDirection.index + 1 : 0,
+                nextNodeId ?? -1,
                 previousNodeId ?? -1,
                 transform,
                 children,);
@@ -446,6 +448,7 @@ class SemanticsUpdateBuilder extends NativeFieldWrapperClass2 {
     String increasedValue,
     String decreasedValue,
     int textDirection,
+    int nextNodeId,
     int previousNodeId,
     Float64List transform,
     Int32List children,

lib/ui/semantics/semantics_node.h

@@ -76,6 +76,7 @@ struct SemanticsNode {
   std::string increasedValue;
   std::string decreasedValue;
   int32_t textDirection = 0;  // 0=unknown, 1=rtl, 2=ltr
+  int32_t nextNodeId = -1;
   int32_t previousNodeId = -1;
 
   SkRect rect = SkRect::MakeEmpty();

lib/ui/semantics/semantics_update_builder.cc

@@ -52,6 +52,7 @@ void SemanticsUpdateBuilder::updateNode(int id,
                                         std::string increasedValue,
                                         std::string decreasedValue,
                                         int textDirection,
+                                        int nextNodeId,
                                         int previousNodeId,
                                         const tonic::Float64List& transform,
                                         const tonic::Int32List& children) {
@@ -71,6 +72,7 @@ void SemanticsUpdateBuilder::updateNode(int id,
   node.increasedValue = increasedValue;
   node.decreasedValue = decreasedValue;
   node.textDirection = textDirection;
+  node.nextNodeId = nextNodeId;
   node.previousNodeId = previousNodeId;
   node.transform.setColMajord(transform.data());
   node.children = std::vector<int32_t>(

lib/ui/semantics/semantics_update_builder.h

@@ -43,6 +43,7 @@ class SemanticsUpdateBuilder
                   std::string increasedValue,
                   std::string decreasedValue,
                   int textDirection,
+                  int nextNodeId,
                   int previousNodeId,
                   const tonic::Float64List& transform,
                   const tonic::Int32List& children);