The ThrowIllegalInvocation runtime function is not used anywhere.

Bug: 
Change-Id: I1bb5386e917f0a4ff787a071cef5e13a3f85ee30
Reviewed-on: https://chromium-review.googlesource.com/600230
Commit-Queue: Yang Guo <yangguo@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47185}