Optimize string "length" property access based on static type
information if possible, but also optimistically optimize the access
based on type feedback from the LoadIC.

R=jarin@chromium.org

Committed: https://crrev.com/17add22ff4b9c5ca638502e7708f0d9d99baca40
Cr-Commit-Position: refs/heads/master@{#29543}

Review URL: https://codereview.chromium.org/1216593003

Cr-Commit-Position: refs/heads/master@{#29588}

Revert of [turbofan] Optimize string "length" property access based on types. (patchset #2 id:20001 of https://codereview.chromium.org/1216593003/)

Reason for revert:
Causes crash when running benchmarks/octane/regexp.js on ARM:
http://build.chromium.org/p/client.v8/builders/V8%20Arm/builds/2492/steps/Benchmarks/logs/regexp

Original issue's description:
> [turbofan] Optimize string "length" property access based on types.
>
> Optimize string "length" property access based on static type
> information if possible, but also optimistically optimize the access
> based on type feedback from the LoadIC.
>
> R=jarin@chromium.org
>
> Committed: https://crrev.com/17add22ff4b9c5ca638502e7708f0d9d99baca40
> Cr-Commit-Position: refs/heads/master@{#29543}

TBR=mstarzinger@chromium.org,jarin@chromium.org,bmeurer@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/1224083002

Cr-Commit-Position: refs/heads/master@{#29544}

Optimize string "length" property access based on static type
information if possible, but also optimistically optimize the access
based on type feedback from the LoadIC.

R=jarin@chromium.org

Review URL: https://codereview.chromium.org/1216593003

Cr-Commit-Position: refs/heads/master@{#29543}