Bug 1653421 - Part 3: Don't normalize marker beyond editable root. r=morgan

When in an editable container, text markers are expected to not go past or before the editable root.

Differential Revision: https://phabricator.services.mozilla.com/D84055

accessible/mac/GeckoTextMarker.h

@@ -56,6 +56,8 @@ class GeckoTextMarker final {
 
  private:
   uint32_t CharacterCount(const AccessibleOrProxy& aContainer);
+
+  bool IsEditableRoot();
 };
 
 class GeckoTextMarkerRange final {

accessible/mac/GeckoTextMarker.mm

@@ -100,6 +100,24 @@ bool GeckoTextMarker::operator<(const GeckoTextMarker& aPoint) const {
   return false;
 }
 
+bool GeckoTextMarker::IsEditableRoot() {
+  uint64_t state =
+      mContainer.IsProxy() ? mContainer.AsProxy()->State() : mContainer.AsAccessible()->State();
+  if ((state & states::EDITABLE) == 0) {
+    return false;
+  }
+
+  AccessibleOrProxy parent = mContainer.Parent();
+  if (parent.IsNull()) {
+    // Not sure when this can happen, but it would technically be an editable root.
+    return true;
+  }
+
+  state = parent.IsProxy() ? parent.AsProxy()->State() : parent.AsAccessible()->State();
+
+  return (state & states::EDITABLE) == 0;
+}
+
 void GeckoTextMarker::NormalizeNext() {
   if (AtEnd()) {
     // If this is the end of the current container, mutate to its parent's
@@ -109,6 +127,7 @@ void GeckoTextMarker::NormalizeNext() {
                                               : mContainer.AsAccessible()->EndOffset();
 
     if (endOffset != 0) {
+      if (!IsEditableRoot()) {
         mContainer = mContainer.Parent();
         mOffset = endOffset;
 
@@ -116,6 +135,7 @@ void GeckoTextMarker::NormalizeNext() {
         // or innermost link if at the beginning.
         NormalizeNext();
       }
+    }
   } else {
     AccessibleOrProxy link;
 
@@ -146,6 +166,7 @@ void GeckoTextMarker::NormalizePrevious() {
                                                 : mContainer.AsAccessible()->StartOffset();
 
     if (startOffset != 0) {
+      if (!IsEditableRoot()) {
         mContainer = mContainer.Parent();
         mOffset = startOffset;
 
@@ -153,6 +174,7 @@ void GeckoTextMarker::NormalizePrevious() {
         // or innermost link if at the end.
         NormalizePrevious();
       }
+    }
   } else {
     AccessibleOrProxy link;