fix(core): ldml backspace processing should delete all markers

- current code would only delete a single marker and fall through
- should loop consuming all markers until a non-marker char is hit

core/src/ldml/ldml_processor.cpp

@@ -227,7 +227,7 @@ ldml_processor::process_key_up(ldml_event_state &ldml_state)
 void
 ldml_processor::process_backspace(ldml_event_state &ldml_state) const {
   if (!!bksp_transforms) {
-    // process with an empty string voa the bksp transforms
+    // process with an empty string via the bksp transforms
     auto matchedContext = process_output(ldml_state, std::u32string(), bksp_transforms.get());
 
     if (matchedContext > 0) {
@@ -245,15 +245,16 @@ void ldml_event_state::emit_backspace() {
   // attempt to get the last char
   // TODO-LDML: emoji backspace
   auto end = state->context().rbegin();
-  if (end != state->context().rend()) {
+  while (end != state->context().rend()) {
     if ((*end).type == KM_CORE_CT_CHAR) {
       actions.code_points_to_delete++;
       state->context().pop_back();
       return;
     } else if ((*end).type == KM_CORE_BT_MARKER) {
-      // nothing in actions
+      // remove any markers before char
       state->context().pop_back();
-      // falls through - end wasn't a character
+      end++;
+      // loop again
     }
   }
   /*