Each DOM node has the corresponding V8 wrapper object. This leads to
apparent duplication in the heap snapshot and may confuse the users.

This patch allows the embedder to specify V8 wrapper for each embedder
node. In the heap snapshot the wrapper node will be merged into the
embedder node. The resulting node will have the same properties as
the embedder node. If the wrapper node name has a tag, then the tag
is also added to the merged node.

Bug: chromium:811925

Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Change-Id: I2492f5b28163a78aee707b9ced1b09ac4b203e3f
Reviewed-on: https://chromium-review.googlesource.com/919482
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Alexei Filippov <alph@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51394}