[WHLSL] Using += causes an exception in StatementCloner
Rewriter.js may need to say let result = new AnonymousVariable(node.origin, Node.visit(node.type, this)); inside visitAnonymousVariable
This is done. *** This bug has been marked as a duplicate of bug 187988 ***
Migrated to https://github.com/gpuweb/WHLSL/issues/104