Reason for revert:
Preparing to land a fix.
Original issue's description:
> Temporarily disable double fields unboxing.
>
> Committed: https://crrev.com/
209cf09ac9e36c1a24cdfa918bc579a4671c6842
> Cr-Commit-Position: refs/heads/master@{#26727}
TBR=jkummerow@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
Review URL: https://codereview.chromium.org/
960173002
Cr-Commit-Position: refs/heads/master@{#26876}
// Determine whether double field unboxing feature is enabled.
#if V8_TARGET_ARCH_64_BIT
-#define V8_DOUBLE_FIELDS_UNBOXING 0
+#define V8_DOUBLE_FIELDS_UNBOXING 1
#else
#define V8_DOUBLE_FIELDS_UNBOXING 0
#endif