Revert "Nested calc() expressions need to consume all their tokens"

This reverts commit 5a426f9babceea8ffa93d870690634371a79457b.

Reason for revert: Caused crbug.com/1430953

Original change's description:
> Nested calc() expressions need to consume all their tokens
>
> When parsing a nested calc() expression that had a valid first part
> (term) that was followed by an invalid operator the parsed part was
> returned to the caller - which had already consumed the tokens within
> the sub-expression. The caller only checked that an expression node was
> returned, which meant that the sub-expression was considered valid.
>
> Require that all tokens that are part of the sub-expression have been
> consumed after parsing has completed to fail the parsing in such a case.
>
> Fixed: 1430413
> Change-Id: I3072e22e2a7b81296510173266814a18fb6bfc37
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4400956
> Auto-Submit: Fredrik Söderquist <fs@opera.com>
> Reviewed-by: Xiaocheng Hu <xiaochengh@chromium.org>
> Commit-Queue: Xiaocheng Hu <xiaochengh@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1126635}

Bug: 1430953,1430413
Change-Id: I866b130615c4328bd4b99716e74e3a045e0f348c
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4404759
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Auto-Submit: Xiaocheng Hu <xiaochengh@chromium.org>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#1126878}

Author: xiaochengh