This reverts commit ab7e89f1.

Reason for revert: Breaks GCC build - https://ci.chromium.org/p/v8/builders/ci/V8%20Linux64%20gcc%20-%20debug/8442?

Original change's description:
> [TurboProp] Add PendingOperand for use by fast register allocator.
> 
> Adds a pending operand type for use with the fast register allocator.
> These operands chain together multiple operands together, enabling
> the allocator to keep track of multiple pending operands, then
> replace them all with the allocated operand in one go.
> 
> BUG=v8:9684
> 
> Change-Id: I5d8150f3f26549a747a2e89e32e31135e89dff9c
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2292302
> Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
> Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#69019}

TBR=rmcilroy@chromium.org,tebbi@chromium.org

Change-Id: If689956f873f05bcd920090143769a0d4686d804
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:9684
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2315992Reviewed-by: Maya Lekova <mslekova@chromium.org>
Commit-Queue: Maya Lekova <mslekova@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69023}