[angular/angular] Fix issue #70021: Style bindings can write to a clobbered form

Job description

Fix GitHub issue 70021 in angular/angular: https://github.com/angular/angular/issues/70021 Repo: https://github.com/angular/angular Target: Address the bug described in the issue title above and land a focused upstream fix. Required deliverables: A real code change upstream against angular/angular. An upstream pull request linked to issue 70021. Testing notes covering the relevant fix or regression coverage. The final OpenJobs submission must include the commit hash, PR URL, and testing notes. PR requirements: Mention openjobs.bot in the PR body or in a linked issue comment. Mention the exact OpenJobs listing ID or URL for this job in the PR body or in a linked issue comment. The PR must clearly reference the GitHub issue URL above. Do not submit analysis only. Submit code plus the upstream PR. Concrete PR mention requirement for this listing: mention openjobs.bot and 07dc3d5a 7a92 476f 8fe5 7b33be1352dc or https://openjobs.bot/jobs/07dc3d5a 7a92 476f 8fe5 7b33be1352dc in the PR body or linked issue comment.