Bug 1386468 - Only register SelectionChangeListener for plaintext controls when dom.select_events.textcontrols.enabled is turned on; r=mystor

layout/generic/nsFrameSelection.cpp

@@ -728,8 +728,13 @@ nsFrameSelection::Init(nsIPresShell *aShell, nsIContent *aLimiter)
     }
   }
 
+  bool plaintextControl = (aLimiter != nullptr);
+  bool initSelectEvents = plaintextControl ?
+                            sSelectionEventsOnTextControlsEnabled :
+                            sSelectionEventsEnabled;
+
   nsIDocument* doc = aShell->GetDocument();
-  if (sSelectionEventsEnabled ||
+  if (initSelectEvents ||
       (doc && nsContentUtils::IsSystemPrincipal(doc->NodePrincipal()))) {
     int8_t index = GetIndexFromSelectionType(SelectionType::eNormal);
     if (mDomSelections[index]) {