This reverts commit 7d699b93.

Reason for revert: Actually we like the trampolines. Slight reduction in code size, and prevents spanning the icache.

Original change's description:
> [ICs] Eliminate trampoline ICs in TurboFan generic lowering
> 
> Trampoline ICs differ from normal ICs only in that they
> load the feedback vector from the stack instead of accepting it
> as an argument. We created them for FullCodeGen, where you always
> have the feedback vector on the stack, and can reduce the amount
> of code required to invoke an ICs by hiding the stack load down
> in the trampoline IC.
> 
> Now the concept isn't really necessary, and we can achieve a
> nice cleanup of our idea-space by removing it. The first step is
> to remove their usage in TurboFan.
> 
> Bug: v8:7199
> Change-Id: I08aefa5de199b1f19adea261b7086a84338c0805
> Reviewed-on: https://chromium-review.googlesource.com/822193
> Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
> Commit-Queue: Michael Stanton <mvstanton@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#50038}

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

Change-Id: I63dcd98b799739d1d6ea55508b1ea5cfad9e3292
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:7199
Reviewed-on: https://chromium-review.googlesource.com/822420Reviewed-by: Michael Stanton <mvstanton@chromium.org>
Commit-Queue: Michael Stanton <mvstanton@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50063}