... and some more cleanup.
The main change is that NativeModule::CloneCode does not relocate the
new code. Wasm functions can only call other trampolines or stubs, or
other wasm functions. Both of these targets are patched later anyway.

This also fixes a bug on arm architectures, where the new call target
(after RelocInfo::apply) could not be encoded in the instruction
correctly. Now the relocation and the patching happen in one step,
avoiding this problem.

R=mstarzinger@chromium.org

Bug: v8:7578

Change-Id: I99a31f9789e7ac811d9b9c0b09bf02b5953d7108
Reviewed-on: https://chromium-review.googlesource.com/971141
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52131}