LockGuard is mostly used with Mutex. Since both are defined outside the
internal namespace, we often have to write
{base::LockGuard<base::Mutex>}. This CL shortens this to
{base::MutexGuard} across the code base

R=mlippautz@chromium.org

Bug: v8:8238
Cq-Include-Trybots: luci.chromium.try:linux_chromium_headless_rel;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: I020d5933b73aafb98c4b72e3bb2dfd07c979ba73
Reviewed-on: https://chromium-review.googlesource.com/c/1278796Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56612}

We were re-definining the FunctionSig typedef in several places. This
CL moves it to value-type.h, since it's a signature over ValueType.

R=titzer@chromium.org

Bug: v8:8238
Change-Id: Id5e8a55c7e0f98d61235e32a5e6cd12e04d26947
Reviewed-on: https://chromium-review.googlesource.com/c/1278387
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Ben Titzer <titzer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56597}

Now that import wrappers are no longer specialized to an index, they
can be cached in the native module, keyed by
(WasmImportCallKind, FunctionSig). This saves instantiation time and
also fixes a (slow) memory leak.

R=mstarzinger@chromium.org

Change-Id: I5197bbfae79d6e811a01289b990db445373eea6c
Reviewed-on: https://chromium-review.googlesource.com/c/1270943
Commit-Queue: Ben Titzer <titzer@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56526}