This reverts commit 31815e73.

Reason for revert: Several failures:
https://ci.chromium.org/p/v8/builders/luci.v8.ci/V8%20Win32/14453
https://ci.chromium.org/p/v8/builders/luci.v8.ci/V8%20Win32%20-%20debug/15144
https://ci.chromium.org/p/v8/builders/luci.v8.ci/V8%20Mac64%20ASAN/18385
https://ci.chromium.org/p/v8/builders/luci.v8.ci/V8%20Win64%20ASAN/3469

Original change's description:
> Reland "[wasm] Enable Liftoff by default on ia32 and x64"
> 
> This is a reland of 20f33823.
> The GC crash should be fixed by https://crrev.com/c/1108208.
> 
> Original change's description:
> > [wasm] Enable Liftoff by default on ia32 and x64
> >
> > R=titzer@chromium.org, hablich@chromium.org
> >
> > Bug: v8:6600, chromium:787421
> > Change-Id: Ia8ae56ddef3b27b0721d5a66ff19abe098a2c6ca
> > Reviewed-on: https://chromium-review.googlesource.com/1109899
> > Reviewed-by: Ben Titzer <titzer@chromium.org>
> > Reviewed-by: Michael Hablich <hablich@chromium.org>
> > Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#53965}
> 
> TBR=titzer@chromium.org, hablich@chromium.org
> 
> Bug: v8:6600, chromium:787421
> Change-Id: I2228084d7bd8ef8e96027bbd3dd81bc42d1dc533
> Reviewed-on: https://chromium-review.googlesource.com/1112097
> Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
> Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#53982}

TBR=titzer@chromium.org,hablich@chromium.org,clemensh@chromium.org

Change-Id: Id53c3cf08fa084108b656b7697786a364dfdf827
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:6600, chromium:787421
Reviewed-on: https://chromium-review.googlesource.com/1112537Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53983}