In case of LAP(lazy accessor pair), the function's creation context
must be equal to the accessor holder's creation context, so this CL
changes the current context to the accessor holder's creation context.

Note that this is the second attempt after https://crrev.com/2770003002

The change from the previous attempt is to skip looking for the
object's constructor if the object itself is a function.

Also some of Blink's LAP-context-sensitive tests got updated at
https://crrev.com/c/597990 and the rest of the tests will get
temporarily disabled at https://crrev.com/c/605408 .

TBR=verwaest@chromium.org

Bug: v8:6156
Change-Id: I09709a90995d82a03996d0347e5a1d8425b5db9c
Reviewed-on: https://chromium-review.googlesource.com/563152
Commit-Queue: Yuki Shiino <yukishiino@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47572}