[compiler][ez] Include phi identifier in AssertValidMutableRanges

Summary:
Looks like we accidentally skipped validating this identifier.

ghstack-source-id: 05964331a812d18430b27dd90c3d5fe9dd8d65d8
Pull Request resolved: #31170

compiler/packages/babel-plugin-react-compiler/src/HIR/AssertValidMutableRanges.ts

@@ -20,6 +20,7 @@ import {
 export function assertValidMutableRanges(fn: HIRFunction): void {
   for (const [, block] of fn.body.blocks) {
     for (const phi of block.phis) {
+      visitIdentifier(phi.id);
       for (const [, operand] of phi.operands) {
         visitIdentifier(operand);
       }