With the introduction of the WasmContext, compiled code is no longer
specialized to the memory start and size (or recently, globals_start).
This CL uses the same WasmContext between the interpreter and compiled
code, removing the need for UpdateMemory() and cached instance info.

R=clemensh@chromium.org

Bug: 
Change-Id: I0bd52352c9b6f3029246e94e239dc29f635e7920
Reviewed-on: https://chromium-review.googlesource.com/712734
Commit-Queue: Ben Titzer <titzer@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48584}