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- Adds kWasmCodeCache to blink::features.
- Checks if enabled before creating the cache in the browser.
- Checks if enabled before fetching from cache in renderer.

This is patterned after the Javascript IsolatedCodeCache feature.

Bug: chromium:719172
Change-Id: I1ffea5d8029b2b550c45e3ba25821889c7c2183c
Reviewed-on: https://chromium-review.googlesource.com/c/1341071
Commit-Queue: Bill Budge <bbudge@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Mythri Alle <mythria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#609705}