Bug 1731886 - Use release asserts for WebIDL union getters. r=peterv

Differential Revision: https://phabricator.services.mozilla.com/D126293

dom/bindings/Codegen.py

@@ -12726,7 +12726,7 @@ class CGUnionStruct(CGThing):
 
             body = fill(
                 """
-                MOZ_ASSERT(Is${name}(), "Wrong type!");
+                MOZ_RELEASE_ASSERT(Is${name}(), "Wrong type!");
                 mValue.m${name}.Destroy();
                 mType = eUninitialized;
                 """,
@@ -12757,7 +12757,7 @@ class CGUnionStruct(CGThing):
 
             body = fill(
                 """
-                MOZ_ASSERT(Is${name}(), "Wrong type!");
+                MOZ_RELEASE_ASSERT(Is${name}(), "Wrong type!");
                 return mValue.m${name}.Value();
                 """,
                 **vars