Ensure @type-scoped protected terms are properly reverted.

Author: dlongley

lib/context.js

@@ -484,6 +484,7 @@ api.createTermDefinition = (
   if(value['@protected'] === true ||
     (defined.get('@protected') === true && value['@protected'] !== false)) {
     activeCtx.protected[term] = true;
+    mapping.protected = true;
   }
 
   // IRI mapping now defined
@@ -982,8 +983,16 @@ api.getInitialContext = options => {
       if(mapping.isTypeScopedTerm) {
         if(mapping.previousMapping) {
           child.mappings.set(term, mapping.previousMapping);
+          if(mapping.previousMapping.protected) {
+            child.protected[term] = true;
+          } else {
+            delete child.protected[term];
+          }
         } else {
           child.mappings.delete(term);
+          if(child.protected[term]) {
+            delete child.protected[term];
+          }
         }
       }
     }