[compiler][ez] Include phi identifier in AssertValidMutableRanges

Summary:
Looks like we accidentally skipped validating this identifier.

[ghstack-poisoned]

Author: mvitousek

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);
       }