--- a/dom/bindings/WebIDLGlobalNameHash.cpp
+++ b/dom/bindings/WebIDLGlobalNameHash.cpp
@@ -51,16 +51,20 @@ struct MOZ_STACK_CLASS WebIDLNameTableKe
 };
 
 struct WebIDLNameTableEntry : public PLDHashEntryHdr
 {
   typedef const WebIDLNameTableKey& KeyType;
   typedef const WebIDLNameTableKey* KeyTypePointer;
 
   explicit WebIDLNameTableEntry(KeyTypePointer aKey)
+    : mNameOffset(0),
+      mNameLength(0),
+      mDefine(nullptr),
+      mEnabled(nullptr)
   {}
   WebIDLNameTableEntry(WebIDLNameTableEntry&& aEntry)
     : mNameOffset(aEntry.mNameOffset),
       mNameLength(aEntry.mNameLength),
       mDefine(aEntry.mDefine),
       mEnabled(aEntry.mEnabled)
   {}
   ~WebIDLNameTableEntry()