This introduces the concept of a jump table for WebAssembly, which is
used for every direct and indirect call to any WebAssembly function.
For lazy compilation, it will initially contain code to call the
WasmCompileLazy builtin, where it passes the function index to be
called.
For non-lazy-compilation, it will contain a jump to the actual code.
The jump table allows to easily redirect functions for lazy
compilation, tier-up, debugging and (in the future) code aging. After
this CL, we will not need to patch existing code any more for any of
these operations.

R=mstarzinger@chromium.org, titzer@chromium.org

Bug: v8:7758
Change-Id: I45f9983c2b06ae81bf5ce9847f4542fb48844a4f
Reviewed-on: https://chromium-review.googlesource.com/1097075
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Ben Titzer <titzer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53805}